What does return on investment (ROI) measure?

Return on investment (ROI) is a financial metric that evaluates the efficiency of an investment or compares the efficiency of several different investments. It specifically measures the ratio of net profit or gain from an investment relative to the costs invested in that project.

In the context of the correct answer, ROI is calculated by subtracting the cost of investment from the revenue generated from the outputs, and then dividing that figure by the cost of the investment. This ratio provides an indication of how well an investment has performed and helps stakeholders make informed decisions about where to allocate resources based on profitability.

The other options address different aspects of project management but do not relate to the financial performance of an investment. The time taken to develop a product is more associated with project scheduling and efficiency rather than profitability. The number of stakeholders involved pertains to project governance and management dynamics rather than financial returns. The amount of work completed might reflect project progress but does not assess the financial outcome of the efforts made. Thus, option B is the most accurate representation of what ROI measures.