Which of the following statements regarding receptor tyrosine kinases (RTK) is TRUE?

a. A receptor tyrosine kinase monomer is able to self-phosphorylate in the absence of a ligand.
b. In order to initiate a downstream cellular response, a receptor tyrosine kinase must activate a signal transduction pathway,
c. In order to initiate a downstream response the activated receptor tyrosine kinase will become Internalized and participate in a phosphorylation cascade.
d. Once bound to its ligand a receptor tyrosine kinase will activate a downstream G-protein by the G-protein associating with its extracellular domain.
e. None of the above are true regarding receptor tyrosine kinases.