Concept:A sole proprietorship is a business owned and controlled by one person. Its capital comes mainly from the owner's savings and small loans.Solution:The owner alone provides the capital, and one person's savings are usually small.Banks often lend only small amounts to one-person businesses because there is little security.So the business finds it hard to raise enough money to grow: inadequate capital for expansion.Option B is wrong because unskilled labour is easy to find; options C and D are not special problems of this form of business.Answer:Option A (inadequate capital for expansion.)