A partnership's internal regulations are set out by

A partnership's internal regulations are typically set out by a deed. A deed is a legal document that records an agreement between two or more parties. In the context of a partnership, a deed is used to outline the rights and obligations of the partners, as well as the rules governing the partnership's operations. The deed typically includes information such as the name of the partnership, the names of the partners, the purpose of the partnership, the amount of capital contributed by each partner, the distribution of profits and losses, and the procedures for admitting new partners or terminating the partnership. The deed is a binding legal agreement, and all partners are required to abide by its terms. So, the correct option for the given scenario is "a deed".