The yellowish fluid "colostrum" secreted by mammary glands of mother during the initial days of lactation has abundant antibodies ( IgA ) to protect the infant. This type of immunity is called as:

Step-by-step solution

Immunity is said to be passive when antibodies produced in other organisms are injected into a person to counteract antigens such as snake venom. The yellowish fluid ‘colostrum’ secreted by the mother during the initial days of lactation is a form of natural passive immunity. It has plenty of antibodies ( IgA ) to protect the infant during the initial months of life. Maternal antibodies ( IgG ) are also transmitted through the placenta. Such an immunity is called natural passive immunity.