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.

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

[EX Q]: Which of these meals would give you most of the nutrients that you need?  
 (A) Meat, milk, and a piece of chocolate (B) Bread, vegetables, and fish (C) Vegetables, fruits, and water (D) Meat, fish, and bread
[EX A]: B

[EX Q]: Which behavior of a dog is the best example of a learned behavior?  
 (A) barking (B) tail-wagging (C) digging a hole (D) coming when called
[EX A]:
D