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.

Example Input: 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
Example Output: B

Example Input: Which will most likely result from a low-pressure weather system?  
 (A) warm temperatures (B) cloudy conditions (C) clear conditions (D) cool temperatures
Example Output: B

Example Input: One type of cold remedy is an effervescent tablet that breaks down in water. When the tablet is placed in water, it forms gas bubbles. In this example, the formation of a gas  
 (A) is a physical property. (B) occurs when adding water to acid. (C) is a sign of a chemical change. (D) occurs when the water boils.
Example Output:
C