The correct answer is A. 1 financial year.
Auditing is a process of reviewing and verifying financial statements to ensure that they are accurate and complete. The definite period of auditing is 1 financial year. This means that an auditor must review and verify the financial statements for the past 12 months.
Option B is incorrect because it is too long. A financial year is typically 12 months, so 2 financial years would be 24 months. This is too long of a period to review and verify financial statements.
Option C is incorrect because it is too short. A financial year is typically 12 months, so 3 financial years would be 36 months. This is too short of a period to review and verify financial statements.
Option D is incorrect because it is too long. A financial year is typically 12 months, so 5 financial years would be 60 months. This is too long of a period to review and verify financial statements.