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 of the following units best represents the density of an object?  
 (A) kg (B) hr (C) m/s^2 (D) g/cm^3
[EX A]: D

[EX Q]: Some people carry a mutated allele of a particular gene that makes them resistant to HIV infection and AIDS. Which best describes this type of mutation?  
 (A) beneficial (B) asexual (C) harmful (D) unicellular
[EX A]: A

[EX Q]: Which statement is describing climate?  
 (A) It snowed 12 centimeters last night. (B) Last winter was colder than normal. (C) There is a thunderstorm watch for the local area. (D) The temperature will be between 32°C and 37°C all week.
[EX A]:
B