There are a number of toothpastes marketed under the Crest brand, including Cavity Protection Crest, Pro-Health Sensitive Shield Crest, Baking Soda Crest, Tartar Protection Crest, and Crest for Kids. This is an example of Crest's:
a) product line width
b) product mix
c) product line depth
d) product mix inconsistency
e) marketing mix
Answer: C