Please use the following financial data: Net sales $200,000 Cost of goods sold $90,000 Operating expenses $80,000 Net income $10,000 Total assets $180,000 Total liabilities $120,000 The gross profit margin is: \begin{tabular}{l} \hline 9% \\ \hline 40% \\ \hline 15% \\ \hline 55% \end{tabular}