Which of the Following Describes the Process of Variolation, Which

Which of the following describes the process of variolation, which was an early method to prevent smallpox infections?

A) Exposure of children to milkmaids infected with cowpox.
B) Quarantine of smallpox victims for 40 days.
C) Use of plant extracts to prevent smallpox infection.
D) Blowing powdered pock scabs into the nose.
E) Exposure of young children to people with an active smallpox infection.