What independence threat arises if fees from an assurance client remain unpaid for a long duration?

The correct answer is that a self-interest threat arises when fees from an assurance client remain unpaid for a long duration. This situation creates a potential conflict of interest for the auditor. When an auditor has a financial stake in the outcome of their service, such as being owed money, their objectivity may be compromised.

The dependence on unpaid fees can lead to the auditor feeling pressured to overlook certain issues or adjust their findings to ensure that they receive payment from the client. This situation can impair the auditor's ability to maintain impartiality and uphold the integrity of their audit work.

Furthermore, this prolonged payment situation could also make the auditor reluctant to challenge the client on significant matters, as doing so might threaten their chances of finally receiving payment. In essence, the unpaid fees create a scenario where the auditor's financial interests may cloud their judgment, undermining the core principles of independence and objectivity essential in auditing.

The other threats mentioned, such as self-review, familiarity, and intimidation, do not directly stem from the issue of unpaid fees. They relate to other forms of pressure or conflict that could affect an auditor's independence but are not specifically tied to financial arrangements with a client.