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: Nonaggressive birds called purple martins nest each spring to lay eggs. Starlings are aggressive birds that will eat the purple martin's eggs and nestlings. Which will most likely be the effect on both populations after a starling invasion?  
 (A) Purple martins will increase and starlings will decrease. (B) Purple martins will increase and starlings will increase. (C) Purple martins will decrease and starlings will decrease. (D) Purple martins will decrease and starlings will increase.
Example Output: D

Example Input: How many basic units of information in a DNA molecule are required to encode a single amino acid?  
 (A) 1 (B) 2 (C) 3 (D) 4
Example Output: C

Example Input: Some students used a hot plate to heat 1 L of water from 20°C to the boiling point of water. The students recorded the temperature of the water each minute until it began to boil. Which of the following provides the most appropriate way to represent the data?  
 (A) a bar graph with temperature on the y-axis and time on the x-axis (B) a bar graph with time on the y-axis and temperature on the x-axis (C) a line graph with temperature on the y-axis and time on the x-axis (D) a line graph with time on the y-axis and temperature on the x-axis
Example Output:
C