B. The cost of accumulating evidence. It would be extremely costly for the auditor to gather enough evidence to be completely convinced. C. Evidence is normally not sufficiently reliable to enable the auditor to be completely convinced. For example, confirmations from customers may come back with erroneous information, which is the fault of the customer rather than the client. D. Even if evidence is not considered highly appropriate or accurate, the auditor may still conclude with a reasonable level of assurance that the financial statements are correct