For Wage Rates Between $7 and $15 Per Hour,Ali's Labor

For wage rates between $7 and $15 per hour,Ali's labor supply curve is backward bending,Ben's labor supply curve is upward sloping,and Charlie's supply curve is vertical at 10 hours of labor supplied.If these three people are the only ones supplying labor in this labor market,then the market labor supply curve will be the sum of the _____

A) labor supply curves of Ali, Ben, and Charlie at each wage rate.
B) upward-sloping portions of Ben's and Ali's labor supply curves.
C) downward-sloping portions of the individual labor supply curves.
D) average of all individual labor supply curves.
E) individual labor supply curves at each net utility for market work.