Which Scope?

Here is a new question for the gun clingers.

Let’s say you get yourself a gun suitable for varmint hunting. You know you’ll probably do all your shooting at 100 yards, but you want to be prepared in case you completely lose your mind, get on a plane, and go shoot prairie dogs. Or maybe God will smile on you, and you’ll move to a place that has a 300-yard range.

What kind of scope do you need?

I have a 9x scope on the K31, and it’s dandy for 100 yards, but I have no idea what you need at higher distances.