Concept:A sole proprietorship is a business owned by one person, and its main challenge is raising enough money to operate.Explanation:The business relies heavily on the owner’s personal savings and small loans.Banks and other lenders are often unwilling to give large amounts of money to a small business with limited assets.The owner therefore finds it difficult to obtain funds for expansion, equipment, or daily running costs.Among the options, sourcing for funds is the most serious problem of a sole proprietor.Answer:D. funds