One advantage of a sole proprietorship is that

A sole proprietorship is a business owned and managed by a single individual. One of its key advantages is that it can be managed without conflicts. Because there is only one owner, all decisions - from day-to-day operations to long-term strategy - rest with that single person. There are no partners or shareholders to disagree with, no board meetings to navigate, and no conflicting visions for the business. This makes decision-making quick and straightforward.

The other options do not describe advantages of sole proprietorship:

• Making an increase in the volume of business possible is actually a limitation of sole proprietorship, since a single owner typically has limited capital and capacity for expansion.
• Raising money from the public is a feature of public limited companies that issue shares on the stock exchange, not sole proprietorships.
• Having no limit to the number of people who may bring in capital describes a public limited company or cooperative, not a sole proprietorship where the owner is the sole source of capital (aside from borrowing).