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 would be more likely to pollute a river?
(A) allowing beavers to build a dam (B) spreading fertilizer near the river (C) mowing the grass on the river bank (D) fishing from a bridge over the river
[EX A]: B

[EX Q]: While conducting an experiment on gravity, what will be needed to ensure the safety of students?
(A) quiet zones (B) drop zones (C) heavy objects (D) frictionless surfaces
[EX A]: B

[EX Q]: Bridge inspectors have determined that a bridge is unsafe. Which of the following is the BEST design process the company should use to correct the problem?
(A) identify the problem-repair the bridge-plan for the repair (B) plan for the repair-repair the bridge-identify the problem (C) plan for the repair-identify the problem-repair the bridge (D) identify the problem-plan for the repair-repair the bridge
[EX A]:
D