<prompt> The protective effects off breast milk are known to be associated withIgM antibodiesLysozymeMast cellsIgA antibodies  <response>: Although antibodies and Lysozyme, both are important for the protective effects of breast milk, antibodies play a major role. Out of IgM and IgA antibodies, breast milk is especially rich in secretory IgA which is the single best answer here.Protective role of breastfeeding against infection Breast milk provides protection against infection because of the following facts -1. The breast milk is clean and uncontaminated2. Breast milk contains several antiinfective factors -Antibodies secretory IgA, IgMLysozymeAntistaphylococcal factorSpecific inhibitory substances against viral infections.Lactoferrin Inhibits growth of E. coli.Bile stimulated lipase kills Entamoeba histolytica and Giardia lamblia.Bifidus factor Inhibits growth of E. coliPara-amino-benzoic acid PABA Provides protection against malariaPhagocytic macrophages and lymphoid cells3. Lower pH of the stool of breastfed infants contributes to the favourable intestinal flora more bifidobacteria and lactobacilli, fewer E. coli. 