Which of These Is Not an Important Principle for the Control

Which of these is not an important principle for the control of cash payments?

A) Employees who sign cheques should not accept delivery of goods.
B) Only senior staff should have the authority to approve invoices for payment.
C) Cheques should be written out promptly even if the invoice is not yet provided.
D) Once the cheque is written the invoice should be stamped 'paid'.