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 is the MAJOR reason Earth has seasons?  
 (A) Earth has a moon (B) Earth has a tilted axis (C) Earth has a magnetic field (D) Earth has an elliptical orbit

Ex Output:
B


Ex Input:
Wave energy from the ocean can be harnessed to power generators to make electricity. Energy from ocean tides can also be used to make electricity. How would you categorize these two sources of energy?  
 (A) Both are renewable. (B) Both are nonrenewable. (C) Wave energy is nonrenewable. Tidal energy is renewable. (D) Wave energy is renewable. Tidal energy is nonrenewable.

Ex Output:
A


Ex Input:
Some scientists once believed that Earth was solid like a marble. Which of these has been most responsible for changes in the scientific view of the structure of Earth?  
 (A) discussions among earth scientists about new data (B) scientific books defining the layers of Earth (C) a lead scientist explaining the structure of Earth (D) a physical model of Earth showing its layers

Ex Output:

A