How is the activation of epidermal growth factor receptor (EGFR) different from that of insulin receptor (IR)?

A) EGFR is a dimer in its inactive and active forms, whereas IR dimerizes only when active.
B) EGFR activation requires dimerization, whereas IR can become activated as a monomer.
C) EGFR is activated by transautophosphorylation, whereas IR activation is phosphorylation-independent and is a simple consequence of receptor dimerization.
D) Unlike IR activation, EGFR activation involves an asymmetric arrangement of the intracellular kinase domains.
E) Both C and D above.