The throw-in at would make an interesting study too. This variation may contain blind spots that can be quite hard to read correctly.
Now, the second throw-in at must be answered by connecting at . If captures at a, then White b results in a ko which White captures first. Now, if plays at b, then captures at c; and if plays at c, then blocks at d.
If ataris from the bottom, then it is sufficient to connect at .