Answer:
b) species
Step-by-step explanation:
A species is a group of individuals that are able to interbreed among themselves. Their progeny is viable and fertile. Since the members of the same species are able to interbreed, gene flow occurs readily between them during the process of sexual reproduction. For example, plants of species Mangifera indica can pollinate each other. When male and female gametes of two plants of Mangifera indica fuse together to form a zygote, genes from these two plants come together in the zygote.