Which type of simple machine is a ramp?

This device blocks an opening along the base/floor of stairs or other walking or working surfaces where materials or body parts might otherwise inadvertently fall through. it should be 4 inches high, with not more than ¼ inch clearance above the floor

In this excerpt, the characters describe the nature of

Based on the context of each quote from incidents in the life of a slave girl by harriet ann jacobs, find the word that most closely matches thedenotation of the bolded word