Protein Kinases Are Enzymes That Transfer the Terminal Phosphate from ATP

Protein kinases are enzymes that transfer the terminal phosphate from ATP to an amino acid residue on the target protein.Many are located in/on the plasma membrane as integral membrane proteins or peripheral membrane proteins.What purpose may be served by their plasma membrane localization?

A) Membrane localization allows for unique protein folding of the protein kinases.
B) Protein kinases can more readily encounter and phosphorylate other membrane proteins.
C) Membrane localization lowers the activation energy of the phosphorylation reaction.
D) Protein kinases flip back and forth across the membrane to access target proteins on either side.
E) Protein kinases require phospholipids as a cofactor.