Final answer:
Passive immunity refers to the transfer of antibodies from mother to infant through the placenta, providing the infant with temporary protection against infections. option 1 is answer
Step-by-step explanation:
The phenomenon you're referring to is passive immunity, more specifically, naturally acquired passive immunity. This type of immunity occurs when antibodies are transferred from the mother to the infant through the placenta to provide protection against potential infections. The infant benefits from the mother's immunological memory, receiving a temporary defense against pathogens.
IgG antibodies are transferred from the maternal circulation to the fetus via the placenta, which is vital for protecting the fetus and the newborn during the first few months of life. Additionally, IgA antibodies present in breast milk also contribute to passive immunity option 1 is answer