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:
Which form of energy is found in food?  
 (A) chemical (B) electrical (C) sound (D) mechanical

Ex Output:
A


Ex Input:
Which energy source is considered nonrenewable?  
 (A) moving water (B) fossil fuel (C) wind (D) biomass

Ex Output:
B


Ex Input:
In a laboratory, a sealed container with 100 g of steam is cooled until all the steam becomes a liquid. The container is then cooled further until all the water becomes a solid. Which of the following remains constant during both of these changes?  
 (A) the mass of the water (B) the pressure in the container (C) the total energy of the water (D) the position of the atoms in the container

Ex Output:

A