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:
The teacher heats a pot of water. Once the water reaches 100°C, which point has the water reached?  
 (A) boiling (B) melting (C) freezing (D) evaporating

Ex Output:
A


Ex Input:
Some birds fly south in the fall and return in the spring. This is an example of  
 (A) migration (B) camouflage (C) hibernation (D) growth

Ex Output:
A


Ex Input:
Many ways of generating electricity use water. An electrical plant using which energy source changes the temperature of water it uses least?  
 (A) nuclear power (B) hydroelectric power (C) natural gas (D) coal

Ex Output:

B