You are given a science question (easy-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:
When microorganisms deplete the oxygen in soil through respiration, the soil becomes  
 (A) humus. (B) anaerobic. (C) compost. (D) aerobic.

Ex Output:
B


Ex Input:
DNA technology has improved greatly in the last twenty years. Which task has been made easier by the development of DNA technology?  
 (A) identifying genetic disorders (B) determining the parts of an atom (C) observing distant objects in space (D) making very accurate measurements

Ex Output:
A


Ex Input:
Which of the following elements is best able to combine with itself and hydrogen [H] to form large molecules?      
 (A) sodium [Na] (B) lithium [Li] (C) sulfur [S] (D) carbon [C]

Ex Output:

D