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:
Patricia and her classmates are visiting different rocky areas in the city. They want to know what kind of rocks can be found in each area. If the investigation is done correctly, what will Patricia and her classmates do each time they visit an area?  
 (A) draw the rock shapes (B) count the rock numbers (C) record the rock types and locations (D) measure the rock masses and lengths

Ex Output:
C


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:
Which material is a good conductor of heat?  
 (A) plastic (B) rubber (C) glass (D) copper

Ex Output:

D