Respuesta :

Answer:

C

Step-by-step explanation:

undefined slope means tat the denominator=0 in the equation

m=y2-y1/x2-x1

A: m=-1-1/1+1=-2

B;2-2/2+2=0

C: 3+3/-3+3 = 6/0 undefined

D: 4+4/4+4=1

Thanks to Swan85, the answer is C.