During an audit of El Salvador Corporation's financial statements, the auditor has found the following control procedures in effect over purchasing and cash disbursements. (a) Purchases are made only from companies that warrant products for workmanship and related damages. (b) Competitive bids are required for all purchases in excess of $10,000 (c) A written memorandum is required for each purchase discount not taken. (d) Receiving reports are prenumbered sequentially and controlled. (e) Voucher packages are canceled immediately after payment. () A procedures manual is maintained for all job functions related to processing purchases and cash disbursements transactions. (g) Postings are verified by check digits in a computer system