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.

[EX Q]: Which plant is grown for food?  
 (A) Rice (B) Tobacco (C) Orchid (D) Cotton
[EX A]: A

[EX Q]: One substance found on Earth is more stable as an elemental gas than as part of a solid compound. As a result, this substance is very abundant in the atmosphere. Which substance exhibits these traits?  
 (A) argon (B) chlorine (C) nitrogen (D) oxygen
[EX A]: C

[EX Q]: Which statement describes a primary function of the cell wall of a plant cell?  
 (A) The cell wall performs photosynthesis. (B) The cell wall stores DNA. (C) The cell wall provides structural support. (D) The cell wall manufactures proteins.
[EX A]:
C