Well, I suppose that the database guys can find out which replies are most frequent in pro play, and that would be interesting information.

That being said, seems a bit unusual, anyway. Would White just play it out of the blue, without supporting strength somewhere? And without knowing about that strength, how can we say what is the best response? Maybe the best response is no response (tenuki).

Also, the one space jump from two stones suggests that White is strong in the area. (Again, this strength is not shown.) Does the question of eyes arise? Can Black afford to sacrifice the single stone?

Keima connection  

Anyway, the keima connection () is a standard way to protect against the cut. at is also a possibility.

at a is possible, looking at a possible sacrifice of .