Refer to the Figure

Refer to the figure.
This graph shows births per woman by year for white and African-American women. Data for African-American women are shown with the green (top) line. What conclusion can be drawn from the information in the graph?

A) A decline in births correlates with a decline in sexual activity.
B) Declining births are due to the availability of the birth control pill.
C) Birth rates for both white and African-American women have declined since 1850.
D) Since 1850, births have declined for white women but not for African-American women.
E) Changes in the institution of marriage have caused a decline in the birth rate.