Explain why each of the following combinations of tasks should or should not be separated to achieve adequate internal control:

a) Approval of bad debt write-offs and the reconciliation of accounts receivable subsidiary ledger and the general ledger control account.

b) Distribution of payroll cheques to employees and approval of employee time cards.

c) Posting of amounts from both the cash receipts and the cash disbursements journals to the general ledger.

d) Writing cheques to suppliers and posting to the cash account.

e) Recording cash receipts in the journal and preparing the bank reconciliation

Please add reference.