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.

Input: Consider 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

Output: C


Input: Consider Input: Which of the following climates has cold winters and hot summers?  
 (A) polar (B) subtropical (C) temperate (D) tropical

Output: C


Input: Consider Input: Which of the following best describes the relationship between frequency and wavelength of electromagnetic waves?  
 (A) If the frequency remains constant, the wavelength increases. (B) The wavelength decreases as the frequency decreases. (C) The frequency increases as the wavelength decreases. (D) If the wavelength remains constant, the frequency increases.


Output: C