I am confused by this question - what is it asking? Is it speaking to what professional body / standards was the auditor subject to? Standards for assurance processes will be different to the standards of the controls, in many cases. 

I would separate assurance processes and controls into two separate questions. 

For example, in a financial statement audit, there may be industry standards for internal controls, ISOs, etc., but the audit is conducted in accordance with (say) Canadian Audit Standards as per the CPA Handbook. If it is the ISO standards of internal controls that are being subjected to assurance for certification purposes, then these assurance standards do not apply.