If rectangle a has a length and width that are z times the length and width of rectangle b, which of the following is true?

a) the perimeter of rectangle a is z times the perimeter of rectangle b.
b) the perimeter of rectangle a is 2z times the perimeter of rectangle b.
c) the perimeter of rectangle a is z^2 times the perimeter of rectangle b.
d) the perimeter of rectangle a is z^3 times the perimeter of rectangle b.

^ means to the power of