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]: In order to maintain good health, humans should  
 (A) eat foods high in fat (B) exercise regularly (C) drink alcohol often (D) smoke tobacco occasionally
[EX A]: B

[EX Q]: The basic life functions of an organism are carried on by  
 (A) cells (B) nutrients (C) atoms (D) hormones
[EX A]: A

[EX Q]: Lemon juice turns litmus paper red, is corrosive and tastes sour. Lemon juice is classified as  
 (A) an acid. (B) a base. (C) an element. (D) More information is needed to classify lemon juice.
[EX A]:
A