The solution is a ko.
at , at , at
If White chooses to capture the snapback stones instead...
White also has this response.
If White loses the ko, this is better because Black will not have played at a.
So in terms of points, this is better for White than the Solution 1 diagram above. However, the other way gives White a local ko threat by capturing the two Black stones as in the Continuation (i) diagram. If that threat is crucial, then the other way is better.
Why is a failure? See Snapback Problem 16.