Describe why scientists use two different models to represent the layers of the Earth.

The answer for your problem would be a. 7

The area they r in. this  the answer.

Each meridian forms half of a great circle, assuming a spherical earth. meridians intersect lines of latitude (parallels) at right angles. the spherical earth is divided into  360 degrees   east-west. lines of longitude range from 0° to  180° to the east and from 0° to -180 ° to the west of the prime meridian.