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]: Wolves have adapted skills for hunting large hoofed animals such as elk, deer, or moose. Wolves tend to target prey animals that are sick or weak. The wolf benefits from this strategy because it uses less energy to hunt. How would the prey animal population also benefit from this strategy?  
 (A) by promoting detrimental genes (B) by stimulating beneficial DNA mutations (C) by preventing the introduction of other predator species (D) by increasing the reproductive success of healthy prey animals
[EX A]: D

[EX Q]: A population of ground squirrels has established a community in the grasslands of the Great Plains. Temperatures often reach -15°C for most of the winter. What is the most likely behavior the ground squirrels use to survive these winter temperatures?  
 (A) burrowing below the frost point of the soil surface (B) burrowing in tree trunks above the soil surface (C) consuming roots found under the soil surface (D) consuming organisms found in the soil surface
[EX A]: A

[EX Q]: The atomic mass of an atom is  
 (A) the same as the atomic number. (B) the same as the group number. (C) the sum of protons and neutrons. (D) the difference between protons and electrons.
[EX A]:
C