Number of units are multiplied to per unit price, to calculate

The correct answer is: C. flexible budget variable.

A flexible budget is a budget that is adjusted to reflect changes in the level of activity. The number of units are multiplied to per unit price to calculate the total revenue, which is a flexible budget variable.

A multiple budget is a budget that is prepared for different levels of activity. A fixed budget is a budget that is prepared for a single level of activity. A constant budget is a budget that does not change, regardless of the level of activity.