I believe the choices from this question are:
a. Michelle's claim that breastfed babies are ill less often because breast milk has the mother's antibodies in it.
b. Deana's assertion that bottlefed babies are less likely to have diarrhea and constipation.
c. Michelle's argument that breastfed babies' psychological development is enhanced.
d. Deana's belief that bottlefed babies make the transition to solid foods more easily.
The answer is:
a. Michelle's claim that breastfed babies are ill less often because breast milk has the mother's antibodies in it.