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: Which characteristic property indicates that igneous rock cools slowly?  
 (A) mineral composition (B) hardness (C) density (D) crystal size
Example Output: D

Example Input: Scientists discovered that although infectious bacteria may develop immunity to antibiotic medications, some bacteria are unable to resist certain peptides, which act as natural antibiotic substances inside the human body. This discovery led to the development of which new technology?  
 (A) artificial substances that mimic human peptides (B) antibiotics that can be absorbed through the skin (C) bacteria that attack antibiotic-resistant organisms (D) antibiotics that adapt in response to bacterial immunity
Example Output: A

Example Input: Cities control the amount of pollution that is allowed to come from cars. How does this most likely help people?  
 (A) The air stays cleaner. (B) Cars can travel at faster speeds. (C) The skills of the drivers improve. (D) It becomes safer to drive on the roads.
Example Output:
A