单项选择题

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 old Black man with a family income in excess of $25,000 expect to live than a 45-year old Black man with a family income of less than $10,000

A.4
B.6
C.8
D.10
E. 12