Final answer:
An example of a unit-based activity driver is direct labor hours, as it varies with the units produced and the volume of activity.
Step-by-step explanation:
An example of a unit-based activity driver is b. Engineering change orders. Activity drivers in cost accounting are measures of the frequency and intensity of the demands placed on activities, and they are used to assign activity costs to products or services. In the context of unit-based activity drivers, we're referring to drivers that relate directly to the units produced or the volume of activity, as opposed to transaction-based drivers which are associated with the number of times an activity is performed.
A unit-based activity driver could be something like direct labor hours, as it varies with the units produced. This wouldn't typically include engineering change orders or material moves, which are often considered transaction-based drivers because they relate to the number of times an activity occurs, not directly to the units produced. Inspection hours can also be considered a unit-based driver if they vary with the units inspected.