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 supply which is consumed during the production of a product. The direct material should be an integral part in the finished good. Consumables are not direct material. To become direct material the raw supplies should be a significant portion of the total cost. There is no direct material in a service business. The finished product should contain the direct material and the material must be an integral part of the final product.