So we know that to transport materials in or out of the cell, we need to have access to both the inside and outside of the cell. This would require that the protein be a transmembrane protein that reaches both the inside and the outside of the cell.
So in this case, let's look at pore proteins. These are proteins that cross a membrane and act as a pore for the materials that need to cross the membrane.
One example of a pore protein is an aquaporin. These proteins aid in the transport of water into or out of a cell.
Therefore, the answer to your question is: A) Pore proteins.
Prokaryotes were the first forms of life on Earth long before simple multicellular life appeared because of their ability to withstand extreme conditions. It is believed that the first living forms were bacteria combined with archaea in the microbial mat (multi-layered sheet).
