A joint venture is a business run under an agreement of two or more parties that operate on an equal percentage basis. They normally are managed by set employees. A corporation is a business registered under more than one individual, and it's typically a large business. A partnership refers to a business agreement between parties to share profits and losses equally. Both partners can be involved in running the business. A proprietorship defines a business operated by an individual. In most cases, the individual is the owner. In terms of size, it's not as big as a corporation or joint venture. Therefore, a neighbourhood barbershop is most likely to be a proprietorship.

The correct answer is A.