An arriving IFR aircraft executing an instrument approach reaches Decision Altitude (DA) and reports no visual contact with the runway environment. What instruction MUST the approach controller expect or issue?

1. Instruct the aircraft to descend an additional 500 ft to seek visual contact
2. Acknowledge and clear/confirm execution of the published Missed Approach Procedure
3. Order an immediate 360-degree orbit at Decision Altitude
4. Hold the aircraft on the glidepath until visual lights appear