A rectangular magazine cover is photocopied by using a scale factor of One-third. The length of the photocopy of the magazine cover is enlarged by a factor of 3. enlarged by a factor of One-third. reduced by a factor of 3. reduced by a factor of One-third.

"reduced by a factor of One-third."

Step-by-step explanation:

Suppose that the original magazine has a length L and a width W.

If it is photocopied using a scale factor of K, then the measures of the photocopy will be:

length = K*L

Width = K*W

In this case, the scale factor is K = 1/3, then the measures of the photocopy will be:

length = (1/3)*L = L/3

Width = (1/3)*W = W/3

For usual notation:

When k > 1, we have an enlargement by a factor k

when 0 < k < 1, we have a reduction by a factor k

in this case, k = 1/3, then:

We have a reduction by a factor of 1/3

The correct option is:

"reduced by a factor of One-third."