Lines m and n are perpendicular. If the slope of m is zero, then the slope of n is

zero

undefined

negative

When two lines are perpendicular to each other, then the product of slopes of both lines is equal to "-1".

Let the slope of line "m" is n1 and slope of line "n" is n2, then;

n1 x n2 = - 1

As per question conditions, n1 = 0;

So n2 = - 1/0

Hence n2 = undefined. Thus 2nd option is correct.