Two arrivals are merging on the same final, currently 6 nm in trail, but they will compress to 2 nm in 4 minutes without action. Standard radar minimum is 3 nm. What is the best planning intervention now?

1. Do nothing — separation is currently 6 nm
2. Issue speed reduction to the lead aircraft and/or vector the trail aircraft to maintain at least 3 nm
3. Cancel both approaches
4. Hand off to another controller without action