Breastfed infants typically are resistant to disease because of
active immunity
passive immunity
immune tolerance
immune memory

Passice immunity

Explanation:

Breast milk, produced by female mammals (including humans), besides being rich in fat and protein is full of IgA. IgA is the immunoglobulin (immune system signal proteins) that is present in body secretions, such as milk.

The baby that is fed from the mother's breast ingests these defense proteins that allow it to tolerate different pathogens and toxins.  

It is considered passive immunity, as it does not generate memory and depends on a continuous dose to maintain defense levels.

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides