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.

Example Input: A student pushes a box to slide it across the floor. Which statement explains why the box begins to move?  
 (A) The weight of the box is greater than the force of friction. (B) The weight of the box is less than the force of friction. (C) The applied force is greater than the force of friction. (D) The applied force is less than the force of friction.
Example Output: C

Example 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.
Example Output: A

Example Input: A teacher is performing a demonstration about static electricity for his class by rubbing a balloon against a wool sweater. The balloon sticks to the wool sweater. Which particles are exchanged during the demonstration?  
 (A) atoms (B) protons (C) neutrons (D) electrons
Example Output:
D