Which of the following is an example of a variable cost?

Housekeeping expenses are an example of a variable cost because they fluctuate based on the level of activity within the property. In real estate management, housekeeping costs can vary depending on factors such as occupancy rates, the size of the property, or the specific services requested by tenants or guests. When occupancy increases, for instance, additional housekeeping staff may be needed to maintain cleanliness, leading to higher costs, whereas lower occupancy would reduce these expenses.

In contrast, property taxes and insurance premiums are fixed costs. They do not change based on how much the property is utilized or occupied; these costs remain stable regardless of the property's performance. Similarly, the general manager's salary is typically a fixed expense, as it is predetermined and does not vary with the number of guests or tenants. Thus, the nature of housekeeping expenses as tied to usage makes it the correct answer as an example of a variable cost.