In this task, you're given an article and an answer. Your task is to generate the question for the answer based on the given article.
One example: Article: There are a lot of public libraries in Britain. These libraries have more than one hundred and fifteen million books, not including those libraries of public schools. Public libraries not only lend books, music records but also help children, patients in hospitals and others to get special play readings, film shows and so on. The first public libraries were founded in about the year 1850. Today's public libraries usually have a reading-room, a lending room and a reference room. The greatest and most famous library in Britain is that of the British Library in London. It was founded in 1973 and has over 10, 000, 000 books. It has nearly every magazine, newspaper and book published in Britain and other parts across the world. 
 Answer: 10,000,000 or less.
Solution is here: How many books are there in the British Library?
Explanation: In the Article, 10,000,000 is mentioned for the number of books available in the British Library, so this is a good question.

Now, solve this: Article: Just five minutes of exercise a day outdoors can improve mental health, according to a study. Researchers from the University of Essex, UK have found that as little as five minutes of a "green activity" such as walking, gardening, cycling or farming could help to improve mood and increase self-esteem  . Many studies have shown that outdoor exercise can reduce the risk of mental illness and improve a sense of well-being, but the new study, led by Jules Pretty and Jo Barton, was the first to determine how much time needed to be spent on green exercise for the benefits to show. Barton and Pretty looked at data from 1,252 people of different ages, genders   and mental health status   taken from 10 studies in Britain. They analyzed their different outdoor activities including walking, gardening, cycling, fishing, boating, horse-riding and farming in locations such as a park, garden or nature trail  . They found that the mental health changes were seen after just five minutes. With longer periods of time exercising in a green environment, the positive effects were more apparent. Looking at men and women of different ages, the researchers found the health changes were particularly strong in the young and the mentally ill. Green and blue A bigger effect was seen with exercise in an area that also contained water - such as a lake or river. "This is because historically we are drawn to water to survive and it is in our genetic   make-up to be at one with nature," the researchers wrote in their report. Pretty said those who were generally inactive, or stressed, or with mental illness would probably benefit the most from "green exercise". "Employers, for example, could encourage staff in stressful workplaces to take a short walk at lunchtime in the nearest park to improve mental health." He also said exercise programs outdoors could benefit youth offenders. 
 Answer: It determined the exact amount of time needed.
Solution:
How is the study this article refers to different from other studies?