A. Option 5 40–45 years. This is the last epoch with a moderate fertility; by this time the primordial ova are four decades old.
B. Option 3 20–25 years. In both sexes most physical characteristics are around the optimal.
C. Option 6 50–55 years. A minute number of conceptions take place around the age of 50; nearly all women have reached the menopause with its surge of gonadotrophins directed at the senescent gonads.
D. Option 1 10–15 years. Changes in fat and hair distribution, the onset of menstruation (menarche) and the adolescent growth spurt usually begin in this epoch.
E. Option 7 60–65 years. Some 15 years after the menopause these changes are associated with withdrawal of oestrogens and progesterone; many women take hormonal replacement therapy during this period; it relieves hot flushes and other symptoms which may be related to the surge in gonadotrophins; some protection against coronary artery disease and osteoporosis can be balanced against adverse long-term effects.