The organization structure chosen by a business owner is determined by a number of factors. These factors may include but are not limited to:
2.) Number of people involved in the business.
3.) Whether there will be employees or not.
4.) A whole host of individual factors.
Strictly speaking in terms of absolute minimum exposure to liability, the business structures that offer the best protection are Corporations (C or S corps) and Limited Liability Companies (LLC). At the other end of the scale, Sole Proprietorship and General Partnerships offer almost no protection against personal liability. Finally you have Limited Liability Partnerships and Limited Partnerships, which offer modest protection against personal liability exposure.