I disagree. Russia MUST not do Option 1. Doing nothing puts him in the half breed’s class and the inevitable comparisons that would arise.
Option 2 with a “Oops” is probably the best option. Light up the Turkish fighters and have an equipment malfunction down one of the Turkish fighters. Follow up with an apology and an offer to replace the jet - with a Russian plane, of course.
It is not about what Russia must, can or could do, but rather what it is forced to do. As I said, Russia is not weak - but it is not at all strong enough to directly take on NATO, and it is doubtful that Putin will take any measures that may even inadvertently trigger such. Which is why I said Option 1 is the most possible, with a tail-end chance for Option 2. I would be very surprised if any real action occurred, as that would mean that Putin is bluffing against a country (Turkey) that just shot down a plane and is thus not bluffing, and the fact that Turkey just called an emergency NATO meeting means that they have mentally thought out possible escalation and are thus pulling the NATO security blanket around themselves. That, by itself, says a LOT.
On the other hand, there is a small chance Putin may go for Option 3, and now that would be something else. Why? Because that's when that decision tree I referred to earlier comes into play, and some of those paths lead to somewhat angry letters and apologies, and others lead to TEOTWAWKI.