The Accounts Receivable Department Must Know When Customers Pay Their

The accounts receivable department must know when customers pay their invoices,yet segregation of duties controls dictate that the collection and recording functions be kept separate from each other.What is a solution to this potential internal control problem?

A) Have customers send a remittance advice with their payment.
B) Have mailroom personnel prepare a remittance list which can be forwarded to accounts receivable.
C) Establish a lockbox arrangement with a bank.
D) all of the above