Which of the following does not represent the same mechanism for avoiding host defenses as the others?
a. Rabies virus attaches to the receptor for the neurotransmitter acetylcholine.
b. Salmonella attaches to the receptor for epidermal growth factor.
c. Lymphocryptovirus (mononucleosis) virus binds to the host receptor for complement protein.
d. Surface protein genes in N. gonorrhoeae mutate frequently.
e. none of the above