Bill Lister contracted with Plimsoll Corporation to complete the roofing on a housing complex. A signed contract established a flat amount for the services rendered by Bill Lister. Bill is a licensed roofer and does his business under the business name, Lister Roofing. He hires his own roofers who are treated as employees for federal employment tax purposes. If there is a problem with the roofing work, Lister Roofing is responsible for paying for any repairs. Bill Lister, doing business as Lister Roofing, is a(n)