Which of the following functions has the steepest slope?

A. Y=-3x-6

B. Y=c+6

C. Y=6x-9

D. Y=2x+12

Your options are all in the slope intercept format

which is

y = mx + b

where m is the slope

so for

A, your slope is - 3

B, slope is 1 (?) [you made a typo]

C, slope if 6

D, slope is 2

the biggest number here is 6

therefore C has your steepest slope