A community comprises of individuals of different species that live together and can also interact in a defied geographical area.
A population refers to the group of individuals that belong to the same species and that can interbreed to produce healthy offspring. Hence, the option (a) is incorrect.
An ecosystem consists of all living organisms along with the non living components of a place. Hence, the option (c) is incorrect.
A biosphere is a collection of biomes, and it is the highest level of organization. Hence, the option (d) is incorrect.
Hence, the correct answer is option (b) community.