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:
Which of these do all cells release?  
 (A) sugar (B) water (C) energy (D) oxygen
answer:
C


question:
Students shake salt into a jar of water, and they shake pepper into a second jar of water. Which statement best compares the two jars?  
 (A) Only the salt and water is a mixture. (B) Only the pepper and water is a solution. (C) Both jars contain solutions. (D) Both jars contain mixtures.
answer:
D


question:
In a rubber duck race, the winning duck traveled 300 meters in 10 minutes. What was the duck's average speed?  
 (A) 0.5 m/s (B) 1.0 m/s (C) 7.5 m/s (D) 30 m/s
answer:

A