In which of the following situations would an auditor ordinarily choose between expressing a qualified opinion or an adverse opinion?

a. The auditor did not observe the entitys physical inventory and is unable to become satisfied as to its balance by other auditing procedures.

b. The financial statements fail to disclose information that is required by generally accepted accounting principles.

c. The auditor is asked to report only on the entitys balance sheet and not on the other basic financial statements.

d. Events disclosed in the financial statements cause the auditor to have substantial doubt about the entitys ability to continue as a going concern.

please explain the answer