What is the meaning of incongruous?

Which element of a short story is most important in "the most dangerous game"? characterization language plot setting symbolism theme

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

What is the relationship between paragraph 2 paragraph 3 through 29?