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 scientific guess about the cause and effect of an event is called  
 (A) a variable. (B) a theory. (C) a hypothesis. (D) an observation.
Example Output: C

Example Input: What is a main feature of plains?  
 (A) a flat, level surface (B) a high, steep peak (C) a low, shallow basin (D) a gentle, gradual slope
Example Output: A

Example Input: A butterfly lays an egg. The egg hatches into a larva. The larva becomes a pupa and then changes into a butterfly. This process is called  
 (A) an adaptation (B) a habitat (C) a food chain (D) a life cycle
Example Output:
D