instruction:
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.
question:
How do most fish get the oxygen they need to survive?
(A) They take in water and break it down into hydrogen and oxygen. (B) Using their gills, they take in oxygen that is dissolved in water. (C) They get their oxygen from the food they eat. (D) They come to the surface every few minutes to breathe air into their lungs.
answer:
B

question:
The body is made up of many systems that interact with one another. For example, the skeletal system and the muscular system work together to help the body move. Which system works with the respiratory system to distribute oxygen to the body?
(A) muscular system (B) digestive system (C) lymphatic system (D) circulatory system
answer:
D

question:
What is at the center of our solar system?
(A) a medium planet with an atmosphere. (B) a star composed of carbon and nitrogen. (C) a black hole that was once a star. (D) a star composed of hydrogen and helium.
answer:
D