Classify the following controls as preventive, detective, or corrective.

a: Periodic bank reconciliation b: Separation of cash and accounting records c: Maintaining backup copies of master and transaction files d: Pre-numbering of sales invoices e: Chart of accounts f: Retina scan before entering a sensitive R and D facility g: Resubmission of transactions for subsequent processing h: Internal auditor rechecking the debits and credits on the payment voucher i: Depositing all cash receipts intact j: Qualified accounting personnel