Final answer:
The answer is Corporation. The three principal forms of business organization are sole proprietorships, partnerships, and corporations.
Step-by-step explanation:
The answer is d. Corporation.
The three principal forms of business organization are sole proprietorships, partnerships, and corporations. A sole proprietorship is a business owned and operated by one person. A partnership is a business owned and operated by two or more people. And a corporation is a large business that has a separate legal entity from its owners.
In this case, a corporation is not one of the three principal forms of business organization mentioned, so the correct answer is d. Corporation.