PLS HELP, IT'S ALMOST DUE! I'LL GIVE BRANLIEST TO THE CORRECT/BEST ANSWER. 40 Points! I'd appreciate if you help :)

A ramp with a constant incline is made to connect a driveway to a front door. At a point 4 feet from the driveway, the height of the ramp is 12 inches. At a point 6 feet from the driveway, the height of the ramp is 18 inches. What is the rate of change of the ramp's incline?

A. 1/3 inch up per foot across
B. 1/2 inch up per foot across
C. 2 inches up per foot across
D. 3 inches up per foot across