In humans the sex chromosomes in a female are a(n) __________ combination, and in males they are a(n) __________ combination

Breastfeeding, rather than bottle-feeding, improves infant mortality rates in:

a. both developing and developed nations b. developing nations but not in developed nations c. developed nations but not in developing nations d. neither developing nor developed nations

According to research discussed in your textbook, becoming a more optimistic thinker begins with:

monitoring your own thinking. trying to develop a Type A personality. suppressing parasympathetic nervous responses. enhancing the use of ego defense mechanisms.