Answer:
D. A mixed cost has a fixed portion that is usually a cost per time period. A mixed cost also has a variable portion that is a cost per unit of cost driver activity.
Explanation:
As we know that
The variable cost is the cost that can change when the level of production increase or decrease
The fixed cost is the cost that remains fixed whether the production level increased or not
ANd, the mixed cost includes some part of the variable cost and some part of the fixed cost
So as per the given options, the option D is correct as the mixed cost involved the fixed portion that could be cost per the time. And, it involved the variable portion i.e cost per unit with respect to the cost driver activity