A Client Asks,"Why Do We Get Some Diseases,like Chickenpox,only Once,but

A client asks,"Why do we get some diseases,like chickenpox,only once,but I get a cold several times a year?" What is the nurse's best response?

A) "The immune system develops a memory for chickenpox,or varicella,but not for colds."
B) "Chickenpox,or varicella,is caused by one virus,while colds are caused by many different viruses."
C) "So many people are immunized against varicella that exposure is rare."
D) "Some people do get varicella more than once."