Answer:
A) comparing the return to the return on invested capital obtained by other firms in the industry.
Step-by-step explanation:
A firm that has developed a competitive advantage over its competitors will to able to either produce the same amount of output using fewer resources, or produce higher output using the same resources than its competitors. A competitive advantage means being more efficient.
So if we want to determine if Zephyr Electronics 18% return on invested capital (ROIC) provides them a competitive advantage over its competitors, we have to compare Zephyr's ROIC with the ROIC of the rest of the major firms in the industry.