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

Ex Output:
A


Ex Input:
Electron transport in mitochondria results in a chemiosmotic gradient of which particle across the mitochondrial membrane?  
 (A) ADP (B) ATP (C) protons (D) neutrons

Ex Output:
C


Ex Input:
Chromium is characterized by a very high melting point. Use the Periodic Table of the Elements to identify which of these elements most likely has a similar melting point.  
 (A) potassium (B) manganese (C) bromine (D) krypton

Ex Output:

B