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.

[Q]: If an ecosystem's balance is disturbed by a volcanic eruption, what will most likely occur?  
 (A) The ecosystem will not change from its original state. (B) The ecosystem will eventually become balanced again. (C) The consumers in the ecosystem will begin to consume carbon dioxide. (D) The consumers in the ecosystem will begin to produce more oxygen.
[A]: B


[Q]: During which process does a caterpillar become a butterfly?  
 (A) fertilization (B) metamorphosis (C) asexual reproduction (D) biological adaptation
[A]: B


[Q]: When a plane flies, it travels through air that contains gases, liquids, and solids. This area is best described as the  
 (A) atmosphere. (B) lithosphere. (C) biosphere. (D) hydrosphere.
[A]:
A