Final answer:
The correct match is a. IgA: Found in secretions such as colostrum, tears, and mucus, as this antibody is present in various secretions and is crucial for mucosal immunity, especially in the protection against pathogens and in immunity transferred to infants through breastfeeding.
Step-by-step explanation:
The correct match from the options provided is: a. IgA: Found in secretions such as colostrum, tears, and mucus. Immunoglobulin A (IgA) is present in various secretions that are critical for protecting mucosal surfaces of our body. It is commonly found in a dimeric form in secretions and is a crucial component of the immune response on our body's exteriors.
IgA assumes a vital role in the defense against digestive and respiratory pathogens, and it is also significant in passing immunity to an infant through breastfeeding. It does not typically exist as a pentamer which is the structure usually associated with IgM. IgG, not IgA, is the main antibody passed from the mother to the unborn child through the placenta. IgM, not IgG, is the first immunoglobulin produced in a primary immune response. IgE is mainly associated with allergic responses and does not typically form pentamers.