You are given a science question (hard-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.

Surface mining is a type of mining that is done at the surface of Earth. In addition to supplying valuable minerals to industry, surface mining might also  
 (A) discourage landfills. (B) increase Earth's surface area. (C) eliminate groundwater pollution. (D) create recreational ponds and lakes.
D

Which factor would most likely limit the number of mice living in an area?  
 (A) plentiful resources (B) stable climate (C) more predators (D) less competition
C

One year, the oak trees in a park began producing more acorns than usual. The next year, the population of chipmunks in the park also increased. Which best explains why there were more chipmunks the next year?  
 (A) Shady areas increased. (B) Food sources increased. (C) Oxygen levels increased. (D) Available water increased.

B

