At 15 Months of Age,a Child Received a Measles-Mumps-Rubella Vaccine

At 15 months of age,a child received a measles-mumps-rubella vaccine (MMR) .At age 22,she is living with a family in Mexico that has not been vaccinated and she is exposed to measles.Despite the exposure,she does not become infected.Which of the following properties of the adaptive immune system is best illustrated by this scenario?

A) Specificity
B) Diversity
C) Specialization
D) Memory
E) Nonreactivity to self