instruction:
You are given a science question (easy-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.
question:
Organisms contribute to the water cycle mainly through the process of  
 (A) irrigation. (B) evaporation. (C) precipitation. (D) transpiration.
answer:
D


question:
Often organisms seem similar in their outward appearances. For example, a porpoise and a shark seem closely related, but they are not. Such similarity is the result of  
 (A) convergent evolution. (B) adaptive radiation. (C) artificial selection. (D) genetic equilibrium.
answer:
A


question:
Tides, such as those along the coast of Massachusetts, are caused by gravitational attractions acting on Earth. Why is the gravitational attraction of the Moon a greater factor in determining tides than the gravitational attraction of the much larger Sun?  
 (A) Earth is much closer to the Moon than to the Sun. (B) The Sun's gravity is a factor only during the day. (C) The Moon's core has a much greater density than the Sun's core. (D) The Sun's mass is smaller than the mass of the Moon.
answer:

A