What is the relationship between the slopes of two parallel lines?
a) two distinct nonvertical lines are parallel if their slopes are reciprocals; that is, the lines with the queation y = MX + b are parallel if and only if mM = 1 or equivalently m = 1/M.
b) Two distinct nonvertical lines are parallel if they have the same slope; that is, the lines with equations y=mx+b and y=Mx+B are parallel if and only if m=M.
c) Two lines with slopes m≠0 and M≠0 are parallel if and only if mM=−1, or equivalently, m=−1/M.
I think that the answer is b since they need to have the same slope only. Right?