Need i don't get what the question is asking

The slope of cd is which segments are perpendicular to cd ? select each correct answer. gf , where g is at (6, 5)and fis at (10, 2) ef, where e is at (4, 1) and f is at (7,5) lm , where lis at (-2, 3) and m is at (-10, 9) jk , where jis at (1, -2) and k is at (10, – 14) next