Answer:a. dimerization and phosphorylation.
Explanation:
Phosphorylation as well as dimerization are responsible for the activation of the receptor tyrosine kinase.
The dimer forms when two monomers combine together. This process is known as dimerization.
This process activates the monomers and basically add up the ATP molecule to the tyrosine. Proteins are added up to the phosphorylated tyrosine which causes the structural change in the protein. This leads to the cellular response.