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.

Input: Consider Input: Organisms contribute to the water cycle mainly through the process of  
 (A) irrigation. (B) evaporation. (C) precipitation. (D) transpiration.

Output: D


Input: Consider Input: Which statement best describes how birth and death rates compare in a population at carrying capacity?  
 (A) The birth rate is greater than the death rate. (B) The birth rate is less than the death rate. (C) The birth rate is equal to the death rate. (D) The birth rate and the death rate are zero.

Output: C


Input: Consider Input: A class is testing the effect of exercise on heart rate. The heart rate of two students before exercise is compared to their heart rate after running around a track. Which procedure will most likely help the class correctly compare the results of the two students?  
 (A) test students who are the same height (B) have the students run on the same day (C) measure the distance each student runs (D) have the students run for the same amount of time


Output: D