Final answer:
The salary of a regional sales manager is indeed a direct cost of the regional office because it can be clearly associated with that specific cost center. The correct option is A.
Step-by-step explanation:
The statement that a regional sales manager's salary is a direct cost of the regional office in which the sales manager works is TRUE. In cost accounting, direct costs are those that can be directly attributed to a specific cost center, such as a department, project, or region.
Since the regional sales manager works specifically for one regional office and their efforts directly contribute to the functioning and success of that office, their salary is directly associated with that office's costs.