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.

Example Input: The drag of wind results in which feature of ocean surface currents?  
 (A) movement of water away from the equator (B) cyclical variations in the height of high tides (C) reduction in velocity with distance from Earth's poles (D) deflection of water toward the direction of airflow
Example Output: D

Example Input: Two pieces of the same metal are placed on a table. The pieces of metal have the same density, mass, and texture. Which characteristic must be the ONLY difference between the two samples?  
 (A) They have different dimensions. (B) They have different boiling points. (C) They are made up of a different type of matter. (D) They contain a different amount of matter per unit volume.
Example Output: A

Example Input: A questioning mind would be helpful for a scientist because it would lead the scientist to  
 (A) become more creative. (B) distrust the work of other scientists. (C) work to accept published hypotheses. (D) conduct research to confirm or disprove theories.
Example Output:
D