Detailed Instructions: 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.
Q: Which question can be answered through scientific investigation?
(A) How does solar energy affect cloud formation? (B) Why are tigers more beautiful than iguanas? (C) What is the best subject to study at college? (D) Should humans invest in space travel?
A:
A