Answer:
The macromolecules that forms pumps and channels in the cell membrane, allowing the entry and exit of molecules to the cell are protein.
Explanation:
Membrane integral proteins are a type of macromolecule attached to the structure of the membrane and have ends in contact with the cytoplasm and the extracellular medium.
These protein molecules can act as channels and transporters or pumps, to facilitate the passage of substances through the membrane. An example of transmembrane channels are ion channels, while a protein transporter is the sodium potassium ATP-ase pump.
Membrane proteins can also act as surface receptors and enzymes linked to the cell membrane.
The other options are not correct because :
