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]: The burning of fossil fuels affects the atmosphere by  
 (A) adding more heat and carbon dioxide. (B) reducing the amount of necessary heat. (C) taking water vapor out of the atmosphere. (D) putting more oxygen in the atmosphere.
[A]: A


[Q]: In an experiment studying phototropism, students grew bean plants in labeled cardboard milk cartons. Afterward, the plants and soil were properly discarded. Which instruction line BEST conserves the remaining resources?  
 (A) recycle the markers, reuse the milk cartons (B) reuse the markers, discard the milk cartons (C) discard the markers, reuse the milk cartons (D) reuse the markers, recycle the milk cartons
[A]: D


[Q]: Animals that eat both plant matter and meat are referred to as  
 (A) decomposers. (B) scavengers. (C) herbivores. (D) omnivores.
[A]:
D