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.
--------
Question: During which stage of an insect's life cycle does the female lay eggs?  
 (A) nymph (B) larva (C) pupa (D) adult

Answer: D


Question: Many scientists are convinced that an increase of certain gases in the atmosphere is affecting global temperatures. What makes this hypothesis difficult to prove?  
 (A) Trees absorb these gases. (B) Global temperatures are rising. (C) Many variables affect global temperatures. (D) Many human activities produce these gases.

Answer: C


Question: Plants use energy directly from the sun. What do they use the energy from the sun for?  
 (A) to make food (B) to disperse seeds (C) to fertilize the soil (D) to prevent insect damage

Answer:
A