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.

[Q]: How does a parachute sufficiently increase air resistance to allow the parachutist to land safely?   
 (A) by decreasing the force of gravity acting on the parachutist (B) by decreasing the total mass of the parachutist (C) by increasing the surrounding air pressure around the parachute (D) by increasing the total surface area of the parachute
[A]: D


[Q]: What is one condition necessary to produce diamonds?  
 (A) high altitude (B) intense pressure (C) quick cooling (D) low temperatures
[A]: B


[Q]: A student wants to use photography to study a process that occurs during one year. Which of these actions would be best for the student to study?  
 (A) a statue being weathered by acid rain (B) a glacier advancing and retreating (C) tree leaves changing colors (D) soil depth increasing
[A]:
C