What's the population of the United States according to the passage

A．People haven't written much about American youth.
B．Writers have wasted a great deal of their effort(努力)to write about American youth.
C．Much has been written about American youth.
D．Young people's ideas are not important enough to the United States.

A．make up nearly half of the American population
B．are deeply interested in making a better life for all people
C．have not been given a fair chance before now
D．are always finding fault with(挑剔)their parents