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:
Thomas Edison most likely invented the light bulb by using  
 (A) lit candles. (B) atomic models. (C) reflected light. (D) the scientific method.

Ex Output:
D


Ex Input:
How are green plants an important part of the carbon dioxide-oxygen cycle?  
 (A) They add oxygen to the soil. (B) They release oxygen into the air. (C) They fix carbon dioxide in the soil. (D) They store carbon dioxide in roots.

Ex Output:
B


Ex Input:
A ship leaks a large amount of oil near a coastal area. Which statement describes how the oil most likely will affect the coastal habitat?  
 (A) Fish reproduction rates will increase. (B) Water birds will be unable to use their wings. (C) Water plants will be exposed to more sunlight. (D) Coastal plants will have access to more nutrients.

Ex Output:

B