Misty Ray, Ellen Bart, and Miranda Diaz each have her own home and service retail store. To potentially reduce their costs and increase their control over supply channels, they buy a plant that manufactures flowerpots and garden tools.

Each makes an equal cash contribution toward the purchase of the plant, each has an equal capital and profits interest in the plant, and they agree to share all losses equally. They own the plant as tenants in common. The co-owners have a written operating agreement specifying that each has an equal interest in the plant's production, each is responsible for her equal share of expenses, and each owns a proportionate, undivided part of the plant's equipment. The agreement also provides that the plant, as such, does not have the right to market the manufactured flowerpots and garden tools. In lieu of the plant's selling the manufactured computer supplies and equipment to other purchasers, Misty, Ellen, and Miranda agree that each will take one-third of the plant's annual output. Each takes her share of the output, commingles it with other flowerpots and garden tools in their respective home and garden retail stores, and sells it to customers.

Misty, Ellen, and Miranda would like to know whether the plant is a partnership for federal income tax purposes. and what authorities can be used in this case?