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.

Ex Input:
Which change in Earth's surface is most directly related to the water cycle?     
 (A) deposition of sediments (B) uplifting of a mountain (C) formation of ocean trenches (D) movement of tectonic plates

Ex Output:
A


Ex Input:
How many basic units of information in a DNA molecule are required to encode a single amino acid?  
 (A) 1 (B) 2 (C) 3 (D) 4

Ex Output:
C


Ex Input:
Which activity most effectively ensures the proper functioning of osteocytes?  
 (A) increasing the respiratory rate (B) consuming mineral-rich foods (C) reducing stressful exercise (D) drinking ion-free water

Ex Output:

B