Under which of the following circumstances would a disclaimer of opinion be appropriate?

(A) The auditor believes managements estimates of the useful lives of key assets are unreasonable, but management refuses to change the estimates.

(B) Management does not provide reasonable justification for a change in accounting principles.

(C) The chief executive officer is unwilling to sign the management representation letter.

(D) The auditor believes, with evidence, that the chief executive officer has committed material fraud.