<prompt> Blood levels of progesterone are highest during ___.The follicular phase of the ovarian cycleThe luteal phase of the ovarian cycleOvulationMenstruation  <response>: Progesterone concentration in blood is highest following the surge of LH leuteinizing hormone following ovulation.During ovulation, estrogen surges due to positive feedback during the follicular phase.During menstruation, there are sharp declines in estrogen and progesterone due to reduced secretion of LH and FSH. 