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:
When a hammer strikes a nail, the nail  
 (A) exerts balanced forces that helps it from moving. (B) exerts a force equal to the weight of the hammer. (C) exerts an unbalanced force that changes its velocity. (D) exerts an equal and opposite force back on the hammer.

Ex Output:
D


Ex Input:
Solar radiation provides more heat near the equator than near the poles on Earth. The greatest amount of heat is moved away from the equator by  
 (A) ocean currents. (B) aquatic plants. (C) surface winds. (D) tectonic plates.

Ex Output:
A


Ex Input:
A student conducts an experiment with potato slices and salt water. The student wants to determine if a higher concentration of salt will affect the amount of water a potato slice absorbs. Which tool would be best to compare the masses of the potato slices?  
 (A) a balance (B) a ruler (C) a microscope (D) a graduated cylinder

Ex Output:

A