What are the various conditions on the basis of which a retiring auditor may be re-appointed at an annual general meeting as per the Companies Act?

Explanation: Section 139.Appointment of auditors: (9) Subject to the provisions of sub-section (1) and the rules made thereunder, a retiring auditor may be re-appointed at an annual general meeting, if— (a) he is not disqualified for re-appointment; (b) he has not given the company a notice in writing of his unwillingness to be re-appointed; and (c) a special resolution has not been passed at that meeting appointing some other auditor or providing expressly that he shall not be re-appointed.