Sixteen squares are arranged to form a region, as shown. Each square has an area of 400\:m^2. Anna walks along the path 
formed by the outer edges of the region exactly once. Aaron walks along the path 
formed by the inner edges of the region exactly once. In total, how far did Anna and Aaron walk?
Answer Choices
A. 160\:m
B. 240\:m
C. 320\:m
D. 400\:m
E. 640\:m