What is the ideal way to determine total cost for a product a) determining product price based solely on internal costs b) giving more weight to internal costs c) taking into consideration both internal and external costs d) giving more weight to external costs

I think the appropriate answer is C. taking into consideration both internal and external costs.
To determine a product cost we add together the total direct ,material costs, the total direct labor costs and the total manufacturing overhead costs that were incurred during the period to determine the total product costs. The result is then divided by the number of products manufactured during the period to determine the product cost per unit.