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:
A student is investigating which type of soil is best for growing tomato plants from seeds. The student plants four tomato seeds in each of three different containers of soil. Which step of the procedure would help the student get the most reliable results?  
 (A) Place one container in a dark room. (B) Use different types of tomato seeds. (C) Change only the soil type in each container. (D) Water each container with a different amount of water.

Ex Output:
C


Ex Input:
Which scientist is known for his genetics experiments with pea plants?  
 (A) Charles Darwin (B) Gregor Mendel (C) Carolus Linnaeus (D) Robert Hooke

Ex Output:
B


Ex Input:
A student is trying to model an ocean environment. What is the most important factor the student should add to the aquarium in order to make sure that the model is accurate?  
 (A) starfish (B) seaweed (C) salt water (D) coral reef

Ex Output:

C