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)