\begin{tabular}{l} If Boeing produces 9 jets per month, its long-run total cost is \( \$ 9 \) \\ million per month. If it produces 10 jets per month, its long-run total \\ cost is \$11 million per month. Boeing exhibits _- \\ \hline OA) rising marginal cost. \\ \hline OB) falling marginal cost. \\ \hline OC) economies of scale. \\ \hline\end{tabular}

If Boeing's long-run total cost increases from \$9 million to \$11 million when production rises from 9 to 10 jets, it indicates that the addition of one more jet has increased the overall cost significantly. This suggests that the company is experiencing rising marginal costs, as producing each additional unit becomes more expensive. In the context of production, businesses often face various cost behaviors. If a firm encounters rising marginal costs, it usually means that production is becoming less efficient as they scale up. This can result from limited resources or operational bottlenecks. In practice, firms must carefully analyze costs to determine the most efficient production levels and avoid unnecessary increases in expenses.