Which pair of lines are parallel?
a) 2x+2y+2=0,vec(r)=(1,2)+s(1,-1),sinR
b) x+7y-2=0,vec(r)=(2,5)+s(1,7),sinR
c) 3x-4y-2=0,vec(r)=(1,4)+s(-3,4),sinR
d) None of the above