By how much is the traffic between IZABU and Anikpu more than the traffic between IZABU and Ugba?

The image below shows the volume and direction of passenger traffic between IZABU town and its surrounding towns in the year 2001.

Scale: 1 line represents 1,500 persons

A. 1,200
B. 1,500
C. 1,700
D. 1,800

Correct Answer:

Option B = 1,500