Final answer:
The most probable example of an unincorporated organization among the given options is D) Sole proprietorship, which is owned and operated by a single individual without formal incorporation.
Step-by-step explanation:
The most probable example of an unincorporated organization from the options given is D) Sole proprietorship. A sole proprietorship is a business owned and operated by one individual without any formal incorporation. The owner of a sole proprietorship is personally liable for all debts and responsibilities of the business, which differentiates it from the other options listed, such as a Limited Liability Company (LLC) or corporation, both of which provide some form of limited liability protection. Partnerships are also not incorporated; however, they involve two or more individuals in ownership, making sole proprietorship the best example of an unincorporated business entity.