Plasma estrogen levels reach their peak at the end of the luteal phase of the ovarian cycle. a. True
b. False

Plasma estrogen levels reach their peak at the end of the luteal phase of the ovarian cycle.

a. True

Explanation:

A woman's estrogen levels become highest towards the end of her ovulation.  At this point, the woman is naturally prepared for a possible pregnancy.  The occurrence of the highest estrogen levels coincides with the luteal phase, a stage of a woman's menstrual cycle, which occurs after ovulation (or the release of eggs from the ovaries), and before the start of the normal period. This luteal phase has been observed to be within 14 days for all women.  By the end of the luteal phase, the corpus luteum function declines.

during expiration the diaphragm relaxes, which causes the diaphragm to move downwards. the contraction of diaphragm increases the space for expansion of lungs. hence, the diaphragm relaxes and positioned downward during expiration.