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.
Answer:
Cytoplasm is the internal medium for cell transport. it contains the proteins and fluid needed for transport. by changing the conditions of the protein and the fluid content the transport is regulated.
Explanation: