$?$hich of the following poses an internal control problem

Physical inspection of inventory quantity and condition is outsourced to a firm that specializes in this service

Sales representatives have authority to increase customers' credit limits in $$1,000$ increments.

When customer payments are received in the mail, checks are sent to the cashier's office and remittance advices are sent to the accounts receivable department

Products are released from inventory after a warehouse employee and a shipping clerk both sign the pick list