Why is there typically a difference between the balance shown on a bank statement at the end of the month and the amount that is shown in a company's accounting records? (more than one can be correct)

a		because of timing differences such as outstanding checks and deposits in transit
b		because of errors a company may have made in recording a transaction in its accounting records
c		because of transactions that were recorded by the bank, that the company didn't know about until it received the bank statement
d		All of the above are correct.