You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

Ex Input:
What happens when water flows over a rock for a long period of time?  
 (A) erosion (B) flooding (C) breakage (D) evaporation

Ex Output:
A


Ex Input:
In an ecosystem, not all of the energy that is available is used by the organisms. Some energy becomes unavailable before it can be transferred to organisms in the next trophic level. How does the energy most likely become unavailable?  
 (A) The energy is stored as food. (B) The energy is dissipated as heat. (C) The energy is trapped in dead organisms. (D) The energy is moved to another ecosystem.

Ex Output:
B


Ex Input:
A student wants to find out how many different kinds of birds are found in a park. In addition to a bird identification book, the student should use ___.  
 (A) binoculars (B) goggles (C) a microscope (D) a hand lens

Ex Output:

A