With #11! ( explain as well? even a brief explanation is fine.) youu.

The functions given are of the form y=mx+b where m is the slope, which is the rate of change.

I dy/dx=4  you can tell by the slope that the rate of change is 4

II dy/dx=1/2  for the same reason as above

III for this one you need to calculate slope or m

m=(y2-y1)/(x2-x1)

from a few points (12-6)/(2-1)=(18-12)/(3-2)=m=6

So function III has the greatest rate of change.