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.

[Q]: The changing appearances of the nighttime sky over the surface of Earth and eclipses of the Moon have provided evidence that  
 (A) Earth is a sphere. (B) Earth supports life. (C) Earth has a layered atmosphere. (D) Earth is covered mostly with water.
[A]: A


[Q]: When a tree suffers from a decreased ability to transport materials within the phloem, what is directly impacted?  
 (A) volume of water in the xylem (B) flow of necessary nutrients (C) response to environmental factors (D) rate of photosynthesis in leaves
[A]: B


[Q]: When the wax from a candle drips, the wax has reached  
 (A) its boiling point. (B) its melting point. (C) a chemical change. (D) a physical change.
[A]:
B