Final answer:
Activity ratios measure the efficiency of a manager's use of assets to generate sales and profits, with examples including inventory and accounts receivable turnover rates.
Step-by-step explanation:
The class of ratios that focuses on the efficiency and effectiveness of a manager's use of assets within a company is B. activity ratios. These ratios measure how well a company utilizes its assets to generate sales and maximize profits. Common examples of activity ratios include inventory turnover, accounts receivable turnover, and fixed asset turnover. They provide insights into the operational performance of the business. In contrast, solvency ratios deal with a company's long-term financial stability, liquidity ratios assess short-term financial resilience, and operating ratios pertain to the company's operating performance.