The correct answer is: C. Total of sales book carried forward from 2000 to 2200
A trial balance is a list of all the accounts in a ledger, with their balances. The total of the debit balances must equal the total of the credit balances. If the trial balance does not balance, it means that there is an error in the accounting records.
The error in option C will not affect the trial balance because the total of the debit balances will still equal the total of the credit balances. This is because the error is in the total of the sales book, which is a subsidiary ledger. The total of the sales book is not included in the trial balance.
The errors in options A and B will affect the trial balance. In option A, the purchase account is debited instead of the expense account. This will cause the debit balance of the purchase account to be too high and the credit balance of the expense account to be too low. In option B, the purchase return book is overcast by Rs. 500. This will cause the debit balance of the purchase return account to be too high and the credit balance of the accounts payable account to be too low.
The error in option D is not a specific error. It is a general statement that all errors will affect the trial balance. This is not true, as the error in option C will not affect the trial balance.