When a permit is issued, the code requires that one set of approved plans and...

Under the ICC administrative provisions used with the mechanical code, one approved set is retained by the code official, and one approved set is returned to the applicant. The returned set must be kept on the site of the building or job while the authorized work is in progress. That directly matches Option A . It does not require return to the architect, filing with the county clerk, or retention for one year after completion.