The correct option is A compulsory
As per section 139 of the Companies Act, 2013, every company shall, at the first annual general meeting, appoint an individual or a firm as an auditor who shall hold office from the conclusion of that meeting till the conclusion of its sixth annual general meeting and thereafter till the conclusion of every sixth meeting and the manner and procedure of selection of auditors by the members of the company at such meeting shall be such as may be prescribed. This makes audit of the company mandatory in nature.