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 these will reduce the gravitational force between two objects the most?
(A) halving the distance between them (B) doubling the distance between them (C) halving the distance between them and doubling their mass (D) doubling the distance between them and halving their mass

Ex Output:
D

Ex Input:
What is the most likely outcome of the Moon moving away from Earth?
(A) A lunar day is shorter. (B) A lunar eclipse lasts longer. (C) Earth moves closer to the Sun. (D) Earth's tides decrease in size.

Ex Output:
D

Ex Input:
In pea plants, the trait for round seeds is dominant over the trait for wrinkled seeds. If a pure dominant plant with round seeds is crossed with a plant with wrinkled seeds, what can be predicted about the offspring plants?
(A) They will always produce round seeds. (B) They will only produce wrinkled seeds. (C) Each offspring plant will have some round and some wrinkled seeds. (D) Unless the plant with wrinkled seeds was pure recessive, no prediction can be made.

Ex Output:
A