Which is an example of acquisition of natural passive immunity? which is an example of acquisition of natural passive immunity? a person who received his or her yearly influenza vaccine a person who received tetanus antiserum after stepping on a rusty nail a fetus protected from disease by its mothers antibodies a person who acquired the chickenpox?

I believe the answer is when a fetus protected from disease by its mothers antibodies.
Passive immunity is a type of immunity acquired by the transfer of antibody from one individual to another, such as from mother to the offspring. Passive immunity can occur naturally when maternal antibodies are transferred to the fetus through the placenta, and it can also be induced artificially, when high levels of antibodies specific to a pathogen or toxin are transferred to non-immune persons blood.