Why exactly are Walmart's costs lower than its competitors? Examine each element of the cost structure (e.g., COGS, labor, rent, advertising, distribution, technology, etc. as a percentage of total sales) and assess where Walmart's costs are lower than competitorsand why.

a	Because Walmart has an extensive distribution network
b	Because Walmart has great supplier relations
c	Because Walmart uses cutting-edge information technology
d	Because Walmart has very low store costs due to location