One Reason Supply Curves Have an Upward Slope Is Because

One reason supply curves have an upward slope is because

A) increased supply will require increased technology.
B) a higher price brings a greater profit,so firms want to sell more of that good.
C) to have more of the good supplied requires more firms to open.
D) people will pay a higher price when less is supplied.
E) None of the above answers is correct because supply curves have a downward slope.