7 A. Before getting sick
B. After one dose of a vaccine
C. After several doses of a vaccine
D. After recovering from a illness
A person develops natural immunity:
Before getting sick
After one dose of a vaccine
After several doses of a vaccine
After recovering from an illness
Whatdo you want to do with

Explanation:

Before getting sick people often do not expect that they will catch some disease or infection. After they do, they have to take one or several doses of a vaccine and it is depending on the disease that they are having.

They will recover after the vaccine but they will also develop natural immunity in them which means that in that case, they will catcht the same or similar disease so easily again.

d would be your answer