What were the primary uses of the horse for early man

A．To tell readers that horse appeared earlier than human being.
B．To inform us that horses can help us a lot.
C．To introduce the history and characteristics of horses.
D．To introduce the primitive horses to modern man.

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