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:
A biological community is made up of all the  
 (A) populations living in an area (B) natural resources present in an area (C) members of a species on Earth (D) environments on Earth
answer:
A


question:
Plants growing in a pond release a gas that fish need to survive. Which gas do the plants release that fish use?  
 (A) helium (B) hydrogen (C) nitrogen (D) oxygen
answer:
D


question:
Fish can live in lakes that are frozen because liquid water remains below the ice at the surface. Which of these describes a property of water that allows some liquid water to remain in frozen lakes?  
 (A) Water can dissolve many different substances. (B) Water is less dense as a solid than as a liquid. (C) Water has a Mohs hardness of about 2 when it is frozen. (D) Water holds less air at higher temperatures.
answer:

B