Which of the following convey the longest lasting immunity to an infectious agent?

Naturally acquired passive immunity

Artificially acquired passive immunity

Naturally acquired active immunity

Which of the following convey the longest lasting immunity to

1.	Which of the following convey the longest lasting immunity to an infectious agent?
A.	Naturally acquired passive immunity
B.	Artificially acquired passive immunity
C.	Naturally acquired active immunity
D.	All of these
Answer» D. All of these