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-1s __________.

product utility

product form

product class

product mix

product item