Based on the choices given, bacterial cell wall can: a. provides cell rigidity to the cells because of the presence of proteins that can give a shape to any bacteria; c. encloses the cytoplasm to protect the entire organism through permeation properties; d. it controls the passage of molecules in and out of the organisms. There are specialized layers present in the cells that cover the entire cell which means that bacterial cells structure has an outer layer that covers the cell membrane. So the answer would be letter B; because it is not the only boundary of the cell.