Which one of the following statements is not true?

a.	A company using the periodic system does not maintain a continuous record of the physical quantities (or costs) of inventory on hand.
b.	In the periodic system, the costs of acquisition of inventory are not debited directly to an inventory account.
c.	In the perpetual inventory system, recording in detailed subsidiary records can be in units only-not in dollar costs.
d.	When the perpetual system is used, a physical count does not need to be made periodically.