The line graph below displays the annual revenue (solid line) and operating expenses (dashed line) for 'Tech Innovations Inc.' from 2015 to 2020. In which year was the company's *profit margin* (Revenue - Expenses) the greatest?
✓ Correct Answer: Option C
Estimate the difference between revenue and expenses for each year. 2018 shows the largest vertical gap between the solid (revenue) and dashed (expenses) lines, indicating the greatest profit margin.