Zappos is a successful online shoe company. one of the difficulties in running a shoe company is the need to have significant a large number of items in each product line.
a. brand equity
b. product line breadth
c. product line depth
d. product mix depth
e. product mix breadth

Correct option is (C)

Explanation:

Product line depth refers to the number of varieties added to existing product line. In other words, expanding a particular product line by adding further related sub-products or including varieties in already existing product is product line depth.

In shoe business, it is difficult to incorporate product line depth as there are not much scope of adding variety within a product line.