Carmel Department Store has an ERP information system and is planning to issue credit cards to creditworthy customers. To strengthen internal control by making it difficult for one to create a valid customer account number, the company's independent auditor has suggested the inclusion of a check digit which should be placed
a. At the beginning of a valid account number only.
b. In the middle of a valid account number only.
c. At the end of a valid account number only.
d. Consistently in any position.
Answer: D