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]: Which of the following is the main role of flowers found on most flowering plants?  
 (A) to take in air (B) to produce seeds (C) to absorb nutrients (D) to protect the stem
[A]: B


[Q]: Greenhouse gases in the atmosphere absorb infrared radiation from Earth's surface and re-radiates some of it back to Earth. Which of these gases have the most significant impact on the temperature of Earth's atmosphere?  
 (A) nitrogen and argon (B) oxygen and sulfur dioxide (C) carbon dioxide and water vapor (D) hydrochloric acid and hydrogen
[A]: C


[Q]: Which of the following metals will be attracted to a magnet?  
 (A) copper (B) gold (C) iron (D) silver
[A]:
C