Which of the following can be a component of the net operating income calculation?

Net operating income (NOI) is a key metric used in real estate to assess the profitability of an income-producing property. It is calculated by taking the property's gross income and subtracting all operating expenses associated with the property.

In the context of the available choices, both operating expenses and property taxes are essential components of this calculation. Operating expenses include a variety of costs incurred in the operation and management of the property, such as maintenance, management fees, utilities, insurance, and repairs. Property taxes, on the other hand, are a mandatory cost that property owners must pay to local governments, and they directly impact the profitability of the property.

Mortgage payments, however, do not factor into the NOI. They are considered financing costs and are accounted for separately from operational income. Thus, the correct answer highlights the inclusion of both operating expenses and property taxes as critical components in calculating net operating income, reinforcing their significance in evaluating a property's financial performance.