Profitability index. Which statement below represents a reasonable interpretation of the profitability index? The profitability index is an explanation device. Like internal rate of return, it can help a decision-maker to understand the merits of an investment. b. The profitability index is a tie-breaker device. It allows a decision-maker to make a call on two investments with the same internal rate of return. The profitability index is a ranking device, but only for projects with short time horizons. d. The profitability index is a device for grouping investments in categories, e.g. high risk/high reward investments vs low risk/low reward investments