The incorrect answer is The internal check system cannot be strengthened as it is impossible to check the accuracy of each ledger independently. Self-Balancing Ledger: All the ledger accounts are prepared from the balances extracted from the trial balance. Under a double-entry system of accounting, each ledger is self-balancing. Important PointsSince all the ledgers are prepared under a self-balancing ledger system, preparation of trial balance becomes easy and final accounts can be prepared using the individual balances from the trial balance. So, option 1 is contextually correct. Detection of errors in a self-balancing ledger system is quite easy as all the ledgers are prepared using a double-entry system of accounting. Under this, the amount debited is always equal to the amount credited thus if any error arises, it can be detected easily as the totals of the debit and credit column in the trial balance would not match. So, option 3 is also contextually correct. Under a self-balancing system, each ledger is maintained under the double-entry principle, therefore each ledger is self-balancing. So, option 4 is also contextually correct. The internal check system can be strengthened as the accuracy of ledgers can be checked under a self-balancing ledger system. This is due to the fact that each ledger account is prepared on a Double entry system. So, option 2 is contextually incorrect here.