A sales clerk at Schackne Company correctly prepared a sales invoice for \(\$ 5,200\), but the invoice was entered as \(\$ 2,500\) in the sales journal and similarly posted to the general ledger and accounts receivable ledger. The customer remitted only \(\$ 2,500\), the amount on his/her monthly statement. The most effective procedure for preventing this type of error is to

(a) use predetermined totals to control posting routines.

(b) have an independent check of sales invoice serial numbers, prices, discounts, extensions, and footings.

(c) have the bookkeeper prepare monthly statements that are verified and mailed by a responsible person other than the bookkeeper.

(d) have a responsible person who is independent of the accounts receivable department promptly investigate unauthorized remittance deductions made by customers or other matters in dispute.