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:
While conducting an experiment on gravity, what will be needed to ensure the safety of students?  
 (A) quiet zones (B) drop zones (C) heavy objects (D) frictionless surfaces

Ex Output:
B


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

Ex Output:
D


Ex Input:
Which of the following is the major cause of tides?  
 (A) heating of the oceans by the Sun (B) gravitational pull of the Moon (C) earthquakes on the ocean floor (D) changes in wind direction

Ex Output:

B