In this subtask, you will answer a simple science question. Please indicate the correct answer. If you're not sure about the answer, choose the last option "I don't know". Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D', 'E'. The "A"-"D" responses correspond to the answer options mentioned in the input. There is a 5th option "E" which should be used for questions for which you're not sure about the answer (e.g., when the questions do not provide enough information to answer).
Example: Question: When a guitar string is plucked, sound is produced by  (A) the size of the guitar. (B) the metal on the guitar. (C) the wood on the guitar. (D) the vibrations of the string.
Example solution: D.
Example explanation: We know that the vibrations of the string produces sound in a guitar. So, the correct answer has to be "D".

Problem: Question: Members of a planning team build a model of a nearby stream and then block the stream to show how it can form a lake. Which is a limitation of the model?  (A) showing how a nearby town will avoid flooding (B) explaining how the lake will be used for recreation (C) explaining how some of the water can be used for agriculture (D) showing how the dam will affect the plants and animals in the are?

Solution: D.