Segregation of Duties Controls Dictates That the Collection and Recording

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

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