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 occurs as the kinetic energy of water molecules increases?  
 (A) Water vapor becomes ice. (B) Liquid water becomes ice. (C) Water vapor becomes liquid water. (D) Liquid water becomes water vapor.
[A]: D


[Q]: What is the most common element in a star such as the Sun?  
 (A) helium (B) oxygen (C) nitrogen (D) hydrogen
[A]: D


[Q]: Petrified palm trees are found in sedimentary rock near glaciers. The presence of the petrified palm trees most likely provides evidence for which statement?  
 (A) There was once more water in the area. (B) The area was once grassland. (C) The climate in the area was once tropical. (D) There are active faults in the area.
[A]:
C