Hello.
The subatomic particles located inside of the nucleus of an atom consist of protons and neutrons.
Auxins will build up on the lower side of the lower side of the root and inhibit cell growth.
I believe it should be A. The presence of a nucleus. Because for response B, it's not true as prokaryotes and eukaryotes possess cell membranes. It can't be C as their ability to interact with the environment is not as different. This is also true of ability to reproduce.