Final answer:
Breast milk confers passive immunity by transferring antibodies from the mother to the infant.
Step-by-step explanation:
Passive immunity is conferred by breast milk. Antibodies produced in the mother's body are passed to the infant through breastfeeding, providing the infant with temporary protection from common pathogens while their own immune system develops. This is an example of naturally acquired passive immunity, where antibodies are transferred to an individual without requiring their own active immune response.