A 20-year-old female presents with pelvic and back pain severe enough to miss work beginning with the onset of menses. Physical examination supports the diagnosis of primary dysmenorrhea. The most likely cause of her condition is:

a. lack of estrogen.
b. stress.
c. elevated prostaglandins.
d. poor nutrition.

ANS: C
Primary dysmenorrhea is painful menstruation associated with the release of prostaglandins in ovulatory cycles; it is not associated with the lack of estrogen, stress, or poor nutrition.