Which of the following antibody is present in mother's milk?

The correct answer is Option (1) → IgA

Option (1) IgA — Correct. The yellowish fluid colostrum, secreted by the mother in the initial days of lactation, has abundant antibodies of the IgA type. They give the infant passive immunity.

NCERT Extract:
Active and Passive Immunity – “When ready-made antibodies are directly given to protect the body against foreign agents, it is called passive immunity. … The yellowish fluid colostrum secreted by mother during the initial days of lactation has abundant antibodies (IgA) to protect the infant. The foetus also receives some antibodies from their mother, through the placenta during pregnancy. These are some examples of passive immunity.”