Choice "D" is correct. Because the deposit account is fully insured, independence is not considered to be impaired.
Choice "c" is incorrect. It has been held that an auditor who is appointed the stock transfer agent of a corporation is not considered to be independent because the functions of a stock transfer agent are similar to that of a manager of the client.
Choice "a" is incorrect. If fees are owed for more than one year, the auditor is considered to be a creditor of the client, and independence is impaired.
Choice "b" is incorrect. If the client is the auditor's only tenant, the auditor definitely has a financial interest in the client's well being, and this situation impairs independence.