There are a number of toothpastes marketed under the Crest brand, including Cavity Protection Crest, Pro-Health Sensitive Shield Crest, Baking Soda Crest, Tarter Protection Crest, and Crest for Kids. The large variety of toothpastes under the Crest brand is an example of a:a.marketing mix.b.product line.c.product mix.d.product equity.e.product modificatio.