Answer:
a.They must be an integral part of the finished product and be a significant portion of the total product cost
Explanation:
The direct material is the material cost which is directly related to the process of the product at the time of manufacturing the product
It can be an integral part of the finished goods as finished goods are come from direct materials and the work in process cycles.
Moreover, it also included in the total product cost along with the direct labor cost and the manufacturing overhead cost