The financial statements of Wayne Company indicate that large amounts of notes payable to banks were retired during the period under audit. Evaluate the reliability of each of the following types of evidence supporting these transactions:

a. Debit entries in the Notes Payable account.

b. Entries in the check register.

c. Paid checks.

d. Notes payable bearing bank perforation stamp PAID and the date of payment.

e. Statement by client's treasurer that notes had been paid at maturity.

f. Letter received by auditors directly from bank stating that no client indebtedness existed as of the balance sheet date.