Explain how each of the following procedures strengthens a company's internal control:

a. After preparing a check for a cash disbursement, the accountant for Timber Lumber Company cancels the supporting business documents (purchase order, receiving report, and invoice) by stamping them PAID.

b. The salespeople for Phinney Department Store give each customer a cash register receipt along with the proper change. A sign on each cash register states that no refunds or exchanges are allowed without the related cash register receipt.

c. The ticket-taker at the Sunrise Theater tears each admission ticket in half and gives one half back to the ticket purchaser. The seat number is printed on each half of the ticket.

d. John Verde's restaurant provides servers with prenumbered customers' checks. The servers are to void checks with mistakes on them and issue new ones rather than make corrections on them. Voided checks must be given to the manager every day.