William, a cash-basis sole proprietor, had the following receipts and disbursements for the current year: Gross receipts $50,000 Cost of sales 30,000 Other operating expenses 5,000 Personal medical expenses 600 For the current year, what amount should William report as net earnings from self-employment? a. $15,000 b. None of the above c. $14,000 d. $13,400 e. $20,000