Functions of the cell membrane include physical isolation of the cell from its surroundings, regulation of exchange, structural support, and which other function?

Apart from the mentioned functions of a cell membrane, one of the prime functions of a cell membrane is to take part in the communication between the cell and its environment. The cell membrane is one of the most essential components that take part in communication and ensures that the messages are received and decoded appropriately.  

A cell membrane comprises various proteins that plays an essential role in ensuring communication between the cells. These proteins obtain chemical information from other cells known as signaling molecules. When these molecules combine with the cellular membrane’s proteins they stimulate a modification or change in protein conformation, which then transmits the information into the cell and instigates a particular cellular reaction.  

the answer is b.) hydrogen bonds between bases.