types of errors

Which of the following types of error is never indicated when a trial balance is extracted?
Errors of commission
Errors of omission
Errors of principle
Transposition errors

The correct answer is Errors of principle. But according to the explanation, the correct answer should be errors of omission? Is it a mistake?

Explanation: The existence of a transposition error should always be revealed by a trial balance. Errors of omission and commission may or may not be revealed, depending on the nature of the error and whether the error has resulted in a mismatch between debt and credit entries in the general ledger accounts. An error of omission is never revealed, because there have been no entries in the general ledger for the omitted item.