TASK DEFINITION: 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.
PROBLEM: A student finds an animal in the wild. He decides it is a bird because it has  
 (A) fins. (B) scales. (C) feathers. (D) four legs.

SOLUTION: C

PROBLEM: The fusion reaction that fuels the Sun converts hydrogen into  
 (A) carbon. (B) iron. (C) neon. (D) helium.

SOLUTION: D

PROBLEM: Five hundred flies of one species were sprayed with a new insecticide. Twenty-four hours later, nearly all the flies were dead. However, a few survived. Which principle best explains why some flies survived?  
 (A) Animals adapt to new environments. (B) New species develop from survivors. (C) There is variation among individuals within a species. (D) Insecticides may cause genetic mutations.

SOLUTION:
C