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 best describes a mineral?  
 (A) a solid natural material with a crystal structure (B) a material that was once living but has decayed (C) a liquid chemical used to make soil more fertile (D) a nutrient produced by plants that other organisms need
[EX A]: A

[EX Q]: Carlos was playing on a slide on a sunny summer day. Which property of the slide tells Carlos how much energy the slide absorbed from the Sun?  
 (A) the mass (B) the color (C) the height (D) the temperature
[EX A]: D

[EX Q]: A research team wanted to produce a smaller variety of German shepherd dogs. They mated the smallest dogs from different litters for several generations. This is an example of which concept?  
 (A) extinction (B) mutation (C) selective breeding (D) natural selection
[EX A]:
C