The Patient Has a 6-In

The patient has a 6-in.high threshold to enter the house at the primary entrance.The family wants to build a ramp.What is the minimum ramp grade recommended?

A) For every 1 inch of rise there is a corresponding 12 in.of length.
B) For every 4 inch of rise there is a corresponding 12 in.of length.
C) For every 1 inch of rise there is a corresponding 30 inches of length.
D) The minimum ramp grade is dependent on the space available.