Under which of the following circumstances would an auditor most likely issue either a qualified or a disclaimer of opinion?

A. The financial statements contain an immaterial departure from generally accepted accounting principles (GAAP).

B. The auditor performed alternate substantive procedures to provide adequate assurance due to missing documentation.

C. There is substantial doubt about the entity’s ability to continue as a going concern.

D. The client’s attorney refused to respond to the letter of audit inquiry.