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.

Ice will form on small ponds when the temperature drops below 0C. Which property of ice is most beneficial to fish living in these ponds?
(A) Ice has a temperature colder than the temperature of water. (B) Ice absorbs sunlight that is reflected by water. (C) Ice traps more pollution than is trapped by water. (D) Ice had a density lower than the density of water.
D

Water in the solid phase has a crystal structure which keeps molecules farther apart than water at certain temperatures in the liquid phase. This relationship explains which property?
(A) the presence of more impurities in ice than in liquid water (B) the ability of ice to float on liquid water (C) the release of heat when liquid water turns into ice (D) the cooling of liquid water as it flows over ice
B

The trait for flower color is highly variable among certain species of rose plants, leading to the formation of flowers of different colors. How did the flower color variation in rose plants come about?
(A) through mutation (B) through pollination (C) through natural selection (D) through asexual reproduction
A