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:
The weight of an object can change even when the mass stays the same. Which statement correctly identifies a relationship between mass and weight?
(A) The weight of an object depends on its mass and its volume. (B) Gravity affects the weight of an object but not its mass. (C) The mass of an object depends on its weight and size. (D) Magnetic fields can affect mass but not weight.

Ex Output:
B

Ex Input:
22 Sandy is conducting an investigation to find out which food his dog likes best. Which is the manipulated variable in his investigation?
(A) The color of his dog's food dish (B) The kind of food he gives his dog (C) The amount of food he gives his dog (D) The time of day he feeds his dog

Ex Output:
B

Ex Input:
Secondary succession is a process that reestablishes a previously colonized, but disturbed or damaged habitat. Which will most likely result in colonization by large herbivores and carnivores?
(A) saplings and trees (B) grasses and shrubs (C) lichens and mosses (D) seedlings and bushes

Ex Output:
A