$16.$ Sargent, CPA, has audited the financial statements of Bay South Incorporated for seven years. Last year's audit fees are not yet paid because the client is experiencing cash flow problems. The audit starts next month. With respect to the past due audit fees, Sargent should:

a$.$ Start the audit as usual.

b$.$ Arrange a fee payment schedule and start the audit as usual.

c$.$ Inform Bay South that the unpaid fees are an impairment of the auditor$$s independence

d$.$ Inform Bay South that unpaid fees are an interest$-$bear obligation and establish an interest rate before proceeding with the audit.