TASK DEFINITION: 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.
PROBLEM: Of these research projects, which is the best choice for a student who is interested in environmental issues to study?  
 (A) making cars run on less fuel (B) finding more sites for copper mines (C) making ocean liners bigger and faster (D) replacing human workers with robots

SOLUTION: A

PROBLEM: A potential negative impact of building a dam on a river is that the dam   
 (A) prevents sediment from flowing downstream. (B) increases the amount of water available to farms. (C) prevents seasonal downstream flooding. (D) increases the rate of water loss from a lake.

SOLUTION: A

PROBLEM: Insulin is an important protein for the regulation of glucose levels in the blood. Which statement best describes the function of insulin?  
 (A) Insulin stimulates cells to absorb glucose from the blood. (B) Insulin causes the liver to release glucose into the blood. (C) Insulin facilitates the effects of antibiotics in the cell. (D) Insulin develops chemical bonds on the cell membrane.

SOLUTION:
A