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]: Several horses grazed in a fenced area across from a home. On rainy days, soil would wash down a slope and run toward the home. After the horses were moved a few years later, the soil no longer washed down when it rained. What could account for this change?  
 (A) The grass grew and kept the soil intact. (B) The fence kept the soil contained. (C) The soil was completely gone. (D) The amount of rain decreased.
[A]: A


[Q]: Which of these has the greatest capacity for storing thermal energy from the Sun?  
 (A) air (B) land (C) oceans (D) plants
[A]: C


[Q]: Some students are performing hardness tests on several substances. X scratches Y. Y scratches Z. Z scratches W. Which of these statements best describes substance W's hardness?  
 (A) W is the softest of the four substances tested. (B) W is the hardest of the four substances tested. (C) W can scratch Y. (D) W can scratch X.
[A]:
A