in case of a newsagent's shop, which of the following is an error of principle?

a. a sale is not recorded in the double entry accounting records

b. a credit sale to A.Barker is entered on the credit side of the sales account and on the deit side of A.Barkers account

c. The cost of purchasing a photocopier on credit is entered on the debit side of the purchases account and on the credit side of the creditor account.

d. None of the above.