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 Input:
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 Output:
A


Ex Input:
A population of plants growing on an island consisted of two varieties, one with thorns and the other without. Over a period of many years, the variety with thorns gradually disappeared. Which process most likely brought about this change in the plant population?  
 (A) gene flow (B) genetic drift (C) natural selection (D) random mutation

Ex Output:
C


Ex Input:
Earth's magnetosphere is not uniformly shaped. It is compressed on the side facing the Sun and has a long tail extending away from the Sun. Which phenomenon is responsible for this shape?  
 (A) centripetal force of Earth's rotation (B) gravitational attraction between Earth and the Sun (C) solar winds bringing high-energy particles toward Earth (D) differences in the distance between Earth and the Sun during Earth's orbit

Ex Output:

C