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 Input:
Which of the following actions will increase the gravitational force between two masses, m_{1} and m_{2}, by the greatest amount?  
 (A) Halve the mass of m_{1} and halve the distance between m_{1} and m_{2}. (B) Halve the mass of m_{1} and double the distance between m_{1} and m_{2}. (C) Double the mass of m_{1} and halve the distance between m_{1} and m_{2}. (D) Double the mass of m_{1} and double the distance between m_{1} and m_{2}.

Ex Output:
C


Ex Input:
Ice will form on small ponds when the temperature drops below 0°C. Which property of ice is most beneficial to fish living in these ponds?  
 (A) Ice has a temperature colder than the temperature of water. (B) Ice absorbs sunlight that is reflected by water. (C) Ice traps more pollution than is trapped by water. (D) Ice had a density lower than the density of water.

Ex Output:
D


Ex Input:
Genes are unable to determine a person's  
 (A) eye color. (B) athletic ability. (C) number of teeth. (D) shape of earlobes.

Ex Output:

B