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.

Example Input: Russell wants to observe changes in nature over the next few months. What can a thermometer help Russell investigate?  
 (A) rainfall amounts each week (B) tiny organisms in pond water (C) the high temperatures each day (D) the amount of growth in a plant
Example Output: C

Example Input: The cheetah population around the world has decreased because of poaching and loss of habitat. The surviving population is found to have similar alleles. Which factor is endangering the species' survival the most?  
 (A) harmful genetic mutations (B) shrinking of the gene pool (C) decrease in competition (D) increase in adaptations
Example Output: B

Example Input: A wetland was drained to build a mall. Two years later, there were no more toads in that area. Why did the toads disappear?  
 (A) The toads were destroyed by the construction equipment. (B) The toads died because toads cannot breathe out of water. (C) The toads were frightened and went into the woods. (D) The toads got their food from the wetland ecosystem.
Example Output:
D