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 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.

Ex Output:
C


Ex Input:
The ounce, the pound, and the ton are units of  
 (A) time. (B) weight. (C) length. (D) distance.

Ex Output:
B


Ex Input:
A lipid bilayer allows certain molecules to pass through and blocks other molecules. Which structure is most often protected by a lipid bilayer?  
 (A) cell (B) organ (C) tissue (D) system

Ex Output:

A