The most useful metric for management to consider when reviewing a project portfolio is the net present value (NPV) of the portfolio. NPV is a measure of the profitability and value of a project or a portfolio of projects, taking into account the time value of money and the expected cash flows. NPV compares the present value of the future cash inflows with the present value of the initial investment and shows how much value is created or lost by undertaking a project or a portfolio of projects1. A positive NPV indicates that the project or portfolio is worth more than its cost and will generate a positive return on investment. A negative NPV indicates that the project or portfolio is worth less than its cost and will result in a loss. Therefore, NPV helps management to prioritize andselect the most profitable and valuable projects or portfolios that align with the organizational strategy and objectives2. The other options are less useful or incorrect because:

A. Cost of projects divided by total IT cost is not a useful metric for reviewing a project portfolio, as it does not reflect the benefits, value, or return of the projects. It only shows the proportion of IT budget allocated to the projects, which may not be indicative oftheir strategic importance or alignment3.

B. Expected return divided by total project cost is not a useful metric for reviewing a project portfolio, as it does not account for the time value of money and the timing of cash flows. It only shows the average return per unit of cost, which may not be comparable across different projects or portfolios with differentdurations, risks, and cash flow patterns4.

D. Total cost of each project is not a useful metric for reviewing a project portfolio, as it does not reflect the benefits, value, or return of the projects. It only shows theinitial investment required for eachproject, which may not be indicative of their profitability or viability5. References: Portfolio, Program and Project Management Using COBIT 5 - ISACA, Project PortfolioManagement - ISACA, CISA Review Manual (Digital Version), Standards, Guidelines, Tools and Techniques