As part of its rebranding from H20 to X-1, the company expanded its “waterproof” product concept to its “waterproof, weatherproof, and sweatproof concept.” In doing so, X-1 added sweatproof headphones, waterproof headphones, and headphones for women to its existing waterproof cases/armband products. Collectively, these products represent X-1’s __________.
product utility
product form
product class
product mix
product item