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.

Example Input: When a person speaks, the type of wave produced can be described as all these except  
 (A) transverse. (B) mechanical. (C) compression. (D) longitudinal.
Example Output: A

Example Input: Russell wants to observe changes in nature over the next few months. What can a thermometer help Russell investigate?  
 (A) rainfall amounts each week (B) tiny organisms in pond water (C) the high temperatures each day (D) the amount of growth in a plant
Example Output: C

Example Input: The atomic number of an element refers to the number of  
 (A) electrons in the outer shell. (B) neutrons in the outer shell. (C) electrons in the nucleus. (D) protons in the nucleus.
Example Output:
D