Final answer:
To compute the margin in an ROI analysis, sales are used in the denominator, resulting in the formula Margin = Operating Income / Sales.
Step-by-step explanation:
In ROI (Return on Investment) analysis, to compute the margin you use the formula where operating income is divided by sales. Thus, for the options provided, the correct answer is: sales in the denominator. Specifically, the formula for the margin in an ROI analysis is:
Margin = Operating Income / Sales
This margin calculation helps in understanding how much profit is being made from the company's sales before taking into account other financial considerations like investment in assets.