Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.
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Question: Context: Organisms that live in lakes, ponds, streams, springs or wetlands are part of freshwater ecosystems. These ecosys- tems vary by temperature, pressure (in lakes), the amount of light that penetrates and the type of vegetation that lives there. Limnology is the study of bodies of fresh water and the organisms that live there. A lake has zones just like the ocean. The ecosystem of a lake is divided into three distinct zones (Figure 1.1): 1. The surface (littoral) zone is the sloped area closest to the edge of the water. 2. The open-water zone (also called the photic or limnetic zone) has abundant sunlight. 3. The deep-water zone (also called the aphotic or profundal zone) has little or no sunlight. There are several life zones found within a lake: In the littoral zone, sunlight promotes plant growth, which provides food and shelter to animals such as snails, insects, and fish. In the open-water zone, other plants and fish, such as bass and trout, live. The deep-water zone does not have photosynthesis since there is no sunlight. Most deep-water organisms are scavengers, such as crabs and catfish that feed on dead organisms that fall to the bottom of the lake. Fungi and bacteria aid in the decomposition in the deep zone. Though different creatures live in the oceans, ocean waters also have these same divisions based on sunlight with similar types of creatures that live in each of the zones. The three primary zones of a lake are the littoral, open-water, and deep-water zones. Wetlands are lands that are wet for significant periods of time. They are common where water and land meet. Wetlands can be large flat areas or relatively small and steep areas. Wetlands are rich and unique ecosystems with many species that rely on both the land and the water for survival. Only specialized plants are able to grow in these conditions. Wetlands tend have a great deal of biological diversity. Wetland ecosystems can also be fragile systems that are sensitive to the amount and quality of water present within them. Click image to the left or use the URL below. URL: Marshes are shallow wetlands around lakes, streams, or the ocean where grasses and reeds are common, but trees are not (Figure 1.2). Frogs, turtles, muskrats, and many varieties of birds are at home in marshes. A salt marsh on Cape Cod in Mas- sachusetts. A swamp is a wetland with lush trees and vines found in low-lying areas beside slow-moving rivers (Figure 1.3). Like marshes, they are frequently or always inundated with water. Since the water in a swamp moves slowly, oxygen in the water is often scarce. Swamp plants and animals must be adapted for these low-oxygen conditions. Like marshes, swamps can be fresh water, salt water, or a mixture of both. As mentioned above, wetlands are home to many different species of organisms. Although they make up only 5% of the area of the United States, wetlands contain more than 30% of the plant types. Many endangered species live in wetlands, so wetlands are protected from human use. Wetlands also play a key biological role by removing pollutants from water. For example, they can trap and use fertilizer that has washed off a farmers field, and therefore they prevent that fertilizer from contaminating another body of water. Since wetlands naturally purify water, preserving wetlands also helps to maintain clean supplies of water. 
 Question: the sloped side of a lake where sunlight penetrates is the

Answer: littoral zone


Question: Context: Future Life Pets By DogTown Media, LLC Open iTunes to buy and download apps. *Price: $2.99 *Category: Lifestyle *Updated: Jan 07, 2012 *Version: 1.1 *Size: 36.3 MB *Language: English *Seller: DOG TOWN MEDIA *(c) DogTown Media LLC Description DISCOVER FUTURE LIFETIMES WITH YOUR PETS You can be transported into the future to be reunited with your pet in another place and time. As an internationally recognized psychic and best-selling author, Anne Jirsch will be your guide in this fascinating meditation game. Future Life Pets will take you into a state of deep relaxation to help you understand this special condition. With expert hypnosis you can discover how your paths will cross in your future lifetime. WHAT PEOPLE ARE SAYING "I immediately saw I was riding a tall black and white horse and you've guessed it --it was my dog and this time he was bigger than ever." --Mike from Kansas City. "Seeing both my cats in the future lifetime has given me so much joy. They are both cats again next time around, only a lot bigger and smoother. I clearly saw them both lie by my feet just as they do right now." --Felicity from Manchester, UK. The regular buyers of Anne's products include heads of industry, politicians, and celebrities of all kinds. She is a world famous psychic and author of three books Instant Intuition, The Future is Yours, and Cosmic Energy. More than a billion people in the world believe in the truth of meditation, through which we'll gain a greater understanding of our pets and ourselves. Prepare for the experience as the results are astonishing. 
 Question: If we want to use the app of Future Life Pets, what kind of language should we know?

Answer: english


Question: Context: Periodic limb movement disorder (PLMD) is one of the commonest neurological disorders and causes significant disability, if left untreated. However, it is rarely diagnosed in clinical practice, probably due to lack of awareness and/or lack of necessary diagnostic facilities. Restless leg syndrome (RLS), aging, pregnancy, uraemia, iron deficiency, polyneuropathy are some of the common causes of secondary PLMD. Clinical presentation, polysomnographic findings and management of six patients of PLMD have been discussed in this report. 
 Question: Which deficiency is the cause of restless leg syndrome?

Answer:
iron


