If Black answers at , White has to make miai of a and b for life.
White can also live by playing at . Black removes the aji with and gets two points more compared to variation 1a.
This looks frightening, but white can capture some stones. (Either a or ''b' next will win the capturing race.)
If White starts here, then a sequence similar to Variation 1a makes Black one point better off. Looking back at 1a, it would be as if White afterwards exchanged for , which effectively gives away 1 point.
What about Black playing the monkey jump right away?
White cuts at and after , Black can't play at a because of shortage of liberties. By the way, at would be a mistake.