A 6-Year-Old Male Is Brought to His Pediatrician's Office with Chickenpox

A 6-year-old male is brought to his pediatrician's office with chickenpox. He has had symptoms for one week, and his mother is concerned about the patient's 8-year-old sister because she had a long, painful chickenpox infection 2 years prior. Of note, the patient was not vaccinated against chickenpox because his parents did not think it was a serious enough virus to warrant the pain of the injection.
-Which of the following explanations correctly represents how this patient could have been protected from chickenpox infection? 

A) He would not have been infected if he were breastfed as a baby because he would have passive natural immunity.
B) He would not have been infected if his mother had gamma globulin administered during pregnancy because he would have passive artificial immunity.
C) He could have been protected from infection if he received active artificial immunity through the form of a vaccine.
D) He may have a primary immunodeficiency disease because healthy humans are not typically infected with chickenpox.