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]: 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
[A]: A


[Q]: The fossils of dinosaurs that lived millions of years ago can be found in  
 (A) the water of oceans. (B) the ice on ponds. (C) the trunks of trees. (D) rocks in the ground.
[A]: D


[Q]: The surface of the Moon is covered with craters. Most of these craters were formed by  
 (A) eruptions of active volcanoes (B) the impacts of many meteoroids (C) shifting rock on the Moon's surface ("moonquakes") (D) tidal forces caused by the Earth and Sun
[A]:
B