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.
--------
Question: What happens to the water vapor in an air mass as it ascends?  
 (A) It freezes. (B) It condenses. (C) It vaporizes. (D) It polarizes.

Answer: B


Question: The ocean minimum zone, or OMZ, is an area from 200 to 600 meters below the ocean's surface. The OMZ is dark and cold, with oxygen concentrations less than 10% of concentrations in surface water. Oxygen concentrations are so low because of bacterial activity that breaks down organic material falling from surface waters. Given the conditions in the OMZ, which of these dissolved gases would you expect to find in large concentrations in this zone?  
 (A) argon (B) nitrogen (C) carbon dioxide (D) carbon monoxide

Answer: C


Question: HIV makes the body vulnerable to secondary infections by targeting  
 (A) macrophages. (B) helper T-cells. (C) cells. (D) killer T-cells.

Answer:
B