Suspense account in specimen

Hello there

Bumble Co extracted the trial balance for the year ended 31 December 2007. The total of the debits exceeded the credits by 300

Which of the following could explain the imbalance?

A Irrecoverable debts of $150 were credited to recievables
B Sales of $300 were omitted from the sales day book
C The bank ledger account did not agree with the bank statement by a debit of $300
D Discounts recieved of $150 was extracted to the debit column of the trial balance

For this question I knew A was wrong since that would require us to credit the supsense account to correct the error. This will only result in the difference increasing by 300

For the next option B..I knew that they have omitted the balance from the daybook and not the trial balance so there should be some sort of double entry to correct the error( credit sales and debit cash)…this correction will not require the use of a suspense account

For the third option I did not know how to correct it

For the fourth option I knew that you need to credit the discount recieved column by 300 ..hence debit the suspense account by 300 and therefore you reduce the suspense account imbalance of 300( which makes D the answer)

The correct answer was obviously D and the revision kit also said D
But I just wanted to know what are the correct procedures to correct the error for option A since I still seem baffled by the existence of that option eventhough I got the answer correct for this question

Thank you