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]: All of the following are functions of a cell membrane except  
 (A) surrounding and protecting the contents of the cell. (B) releasing waste products from the cell. (C) producing energy for cell processes. (D) allowing gases to enter the cell.
[EX A]: C

[EX Q]: In an electric motor, electrical energy is converted into  
 (A) mechanical energy. (B) chemical energy. (C) thermal energy. (D) light energy.
[EX A]: A

[EX Q]: Three main sequence stars are being compared. Which characteristic would these three stars most likely have in common?  
 (A) chemical composition (B) distance from Earth (C) temperature (D) brightness
[EX A]:
A