Answer:
Option B Depreciation expense
Explanation:
The allocation of cost of the plant and equipment for the period being used is the concept of depreciation and is a period cost because when the asset is purchased its value decreases gradually with time which means some of the machinery value would be deminish during the year depending upon the technological factors, life of the equipment, etc. So the period cost will arise regardless of that we either use the asset or not which is the definition of period cost which in this case is depreciation cost and the allocation of cost of plant and equipment over its useful life is also depreciation cost.