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: Which best describes a scientific theory?  
 (A) It is still being tested. (B) It is true, once written. (C) It is different for each continent. (D) It is determined in a court of law.

Output: A


Input: Consider Input: The Grand Canyon is an example of  
 (A) erosion. (B) deposition. (C) an earthquake. (D) volcanic activity.

Output: A


Input: Consider Input: Science students investigated the cause of the different phases of the moon. The model that would best demonstrate the cause of the phases of the moon would include representations of  
 (A) the moon and Earth (B) the moon and the sun (C) the moon, the sun, and Earth (D) the moon, the sun, and Venus


Output: C