Imaginary lines that run from the north pole to the south pole are

meridians of longitude

Explanation:

Meridians of longitude are imaginary half-circles running from the North Pole to the South Pole. They are sometimes called lines of longitude.  Unlike parallels of latitude that are different sizes, all lines of longitude are the same length. Since every meridian must cross the equator, and since the equator is a circle, the equatorial circle can be divided into 360°. These divisions of the equatorial circle are used to label the meridians.

letter d is correct.

d. it adversely affected american productivity