The antibody found in high concentration in colostrum, saliva and tears is

Explanation

IgA is secreted onto mucous surfaces and into milk, where it neutralises pathogens at the point of entry before they can invade, which is one strong reason for breastfeeding. It works outside the tissues, so it is not the antibody that crosses the placenta. IgM, being very large, stays in the bloodstream, and IgE is bound to mast cells rather than free in secretions.