correction of errors

You do not say what you are asking!! Anyway the answer is 'b' because the same figure from the sales day book is entered in both the receivables and the sales accounts. Therefore the trial balance would still balance because both of the balances will be wrong. So there is no suspense account. Suspense accounts and Books of Prime Entry are both explained in full in my free lectures. The lectures are a complete free course for Paper FA and cover everything needed to be able to pass the exam well.

So when question states that Sales return book was under cast by $ 1990 , why do we pass journal entry Sales return account Dr 1990 To Suspense account 1990 Instead of Sales return account Dr 1990 To Trade receivables 1990 Since there is problem in sales return book , it should affect both accounts sales return account as well as trade receivables account .

The first entry is not correct. If the only error is that the sales return book is undercast the there is no entry in the suspense account and it is the second entry you have typed that is correct.