Microevolution is changes in the frequency of genes in a gene pool. According to this definition, what is the smallest biological unti that can evolve?

the genotypes would be 50% bb and 50% bb

the phenotypes would be 50% brown and 50% white. hope this : )

"it built up in the atmosphere"

i think thats it, idk, i tried looking for this exact q& a for grad. and idk if i got this question right or sorry if im wrong

then go eat. lol.brainliest