In which of the following circumstances would an auditor most likely add an explanatory paragraph to the standard report while not affecting the auditor’s unqualified opinion?

The auditor is asked to report on the balance sheet, but not on the other basic financial statements.
There is substantial doubt about the entity’s ability to continue as a going concern.
Management’s estimates of the effects of future events are unreasonable.
Certain transactions cannot be tested because of management’s records retention policy.