Place the Following Steps in Proper Order

Multiple Choice

Place the following steps in proper order:
A.phosphorylation of RTK cytoplasmic tails
B.activation of downstream signaling pathways
C.ligand binding,receptor dimerization,and kinase activation
D.protein binding to RTK phosphotyrosines and phosphorylation of target proteins

A) C, D, A, B
B) C, B, A, D
C) C, A, D, B
D) B, C, A, D