Which of the following business must have at least one member with unlimited liability?

The business that must have at least one member with unlimited liability is a limited partnership. In a limited partnership, there are two types of partners: general partners who have unlimited liability, and limited partners who have limited liability. The limited partners are not personally liable for the debts and obligations of the business, but they also do not have as much control over the business as the general partners do. Therefore, at least one member must be a general partner with unlimited liability in order to ensure that the business can fulfill its obligations.