Concept: The question tests on the basics of rounding and approximation.
Solution:
Total number of regions -= 403 = 400 (rounded)
= 4 x 10^2
Total number of dealers per region = 98 (rounded)= 100
=10^2
Total number of pairs of Brand X shoes sold per dealer = 2488
=2500(rounded)
=25 x 10^2
Total number of shoes sold last year = Regions x dealers x sale/dealer
= 4 x 10^2 X 10^2 X 25 x 10^2
= 4 X 25 X 10^6
=10^8 (option e)