William, a Cash-Basis Sole Proprietor, Had the Following Receipts and Disbursements

William, a cash-basis sole proprietor, had the following receipts and disbursements for the current year: $\begin{array}{llcc} \text { Gross receipts} & \$50,000 \\ \text { Cost of sales } &30,000\\ \text { Other operating expenses } &5,000\\ \text {Personal medical expenses } &600\\\end{array}$
For the current year, what amount should William report as net earnings from self-employment?

A) $13,400
B) $14,000
C) $15,000
D) $20,000
E) None of the above