Final answer:
A proprietorship, especially a sole proprietorship, is a popular small business form because it is easy to start and requires fulfilling a minimal number of legal requirements.
Step-by-step explanation:
The most popular small business form that is easy to start and has few legal requirements is a proprietorship, specifically a sole proprietorship. Sole proprietorships are owned and operated by one individual, making them straightforward to manage. This business model allows the owner to keep all profits, though they must also assume all associated risks. Sole proprietorships do not require the payment of special taxes beyond income tax on the business's profit.
In contrast, a partnership involves two or more individuals and can be a bit more complex, requiring a partnership agreement. Although there are no special taxes for partnerships, the responsibilities and profits are shared among the partners. A corporation, on the other hand, is a more formal and legally structured entity, potentially allowing access to external investment through selling shares but also comes with more complex legal and tax requirements.