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: City administrators can encourage energy conservation by  
 (A) lowering parking fees (B) building larger parking lots (C) decreasing the cost of gasoline (D) lowering the cost of bus and subway fares
Example Output: D

Example Input: An astronomer observes that a planet rotates faster after a meteorite impact. Which is the most likely effect of this increase in rotation?  
 (A) Planetary density will decrease. (B) Planetary years will become longer. (C) Planetary days will become shorter. (D) Planetary gravity will become stronger.
Example Output: C

Example Input: A bicycle is traveling at 3 meters per second (m/s). The rider applies the brakes and stops the bicycle in 3 seconds. What is the average rate of acceleration of the bicycle during this time?  
 (A) -1 m/s^2 (B) -6 m/s^2 (C) 3 m/s^2 (D) 9 m/s^2
Example Output:
A