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: Many things can contribute to the development of a theory. A student made a list of some things that might help scientists develop a theory. Observations Calculations Conversations Publications From the student's list, which must be used in the development of every theory?  
 (A) Observations (B) Conversations (C) Publications and calculations (D) Calculations and conversations

Output: A


Input: Consider Input: A student is dropping objects of various sizes and shapes and recording the time it takes for each object to hit the ground. Which question is the student most likely trying to answer?  
 (A) What force slows some objects down? (B) What force pulls objects to the ground? (C) Do some objects fall more quickly than others? (D) Do objects break or bounce when hitting the ground?

Output: C


Input: Consider Input: What effect does gravity always have on an object on Earth?  
 (A) makes the object move (B) makes the object stay still (C) pushes the object upward (D) pulls the object downward


Output: D