instruction:
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.
question:
Ice will form on small ponds when the temperature drops below 0°C. 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.
answer:
D


question:
While collecting wildflowers, a student begins to sneeze and has itchy, watery eyes. What bodily system causes this reaction?  
 (A) immune (B) nervous (C) muscular (D) circulatory
answer:
A


question:
Which are produced during photosynthesis?  
 (A) carbon dioxide and minerals (B) carbon dioxide and sugar (C) oxygen and minerals (D) oxygen and sugar
answer:

D