Final answer:
The legal forms of business organization are sole proprietorship, partnership, and corporation. The triumvirate is not a recognized business structure. Options A, C and D are correct.
Step-by-step explanation:
The legally recognized forms of business organization in the United States include the sole proprietorship, partnership, and corporation. A sole proprietorship is the simplest form and involves a single owner who manages the business. Partnerships involve two or more people sharing ownership and operation of a business.
Finally, corporations are more complex structures that are legal entities separate from their owners and can sell shares to raise capital. Among the options given, The triumvirate is not a legal form of business organization.
Hence, the correct options are A, C and D.