【单选题】

See the diagram on the following page for information to answer the questions.

In the period from 1979-1989, on average, how much longer, in years, could a 45-year oldBlack man with a family income in excess of $25,000 expect to live than a 45-year oldBlack man with a family income of less than $10,000A．4
B．6
C．8
D．10
E、12