Which of the following legal situations would be considered to impair the auditor’s independence?

a. An expressed intention by the present management to commence litigation against the auditor, alleging deficiencies in audit work for the entity, although the auditor considers that there is only a remote possibility that such a claim will be filed.
b. Actual litigation by the auditor against the entity for an amount not material to the auditor or to the financial statements of the entity arising out of disputes as to billings for management advisory services.
c. Actual litigation by the auditor against the present management, alleging management fraud or deceit.
d. Actual litigation by the entity against the auditor for an amount not material to the auditor or to the financial statements of the entity arising out of a dispute as to billings for tax services.