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 Q]: Which best describes sexual reproduction in all animals?
(A) Egg and sperm join together. (B) Pollen and seed join together. (C) Offspring have traits of only one parent. (D) Offspring are identical to one parent.
[EX A]: A

[EX Q]: 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 A]: B

[EX Q]: Reef-building corals work together with photosynthetic algae that live in their tissues. Which type of energy is algae within a coral reef most likely able to use in order to survive?
(A) chemical (B) mechanical (C) radiant (D) thermal
[EX A]:
C