An activity-based costing system that is designed for internal decision-making will not conform to generally accepted accounting principles because:

a. under activity-based costing the sum of all product costs equals the total costs of the company.

b. under activity-based costing not all manufacturing costs are assigned to products.

c. activity-based costing has not been approved by the United Nation's International Accounting Board.

d. activity-based costing results in less accurate costs than more traditional costing methods based on direct labor-hours or machine-hours.