Which of the following is a financial metric included in a balanced scorecard for measuring business performance?

The selected option focuses on operating margin, which is indeed a crucial financial metric in a balanced scorecard for measuring business performance. The balanced scorecard framework incorporates various perspectives, including financial, customer, internal processes, and learning and growth. Operating margin specifically reflects a company's operational efficiency and profitability by indicating the percentage of revenue remaining after covering operational costs. This metric provides insight into how well a company is managing its expenses and can guide strategic decision-making to improve financial performance over time.

In contrast, while planning abilities and net promoter score offer insights into different aspects of business operations and customer satisfaction, they do not directly measure financial performance. Additionally, PEST analysis is a strategic tool used for assessing external factors affecting a business rather than a financial metric. Therefore, operating margin stands out as the most relevant choice within the context of the balanced scorecard approach to measuring business performance.