This is level 3 of the A-Tunnel.
This level is nearly all crumbling tiles. But you have to jump across platforms, so it is quite difficult.
Child is useful in this level, since he can run on the crumbling tiles without making them crumble. This proves to be useful. And his jump can be far enough to float a long way away, so you just need to care for landing. If you see yourself going to jump into a gap, try to land immediately by moving left/right and touch the platforms on the wall, and this can be useful. Since all the crumbling tiles are apart, you can jump without any consequence, fortunately.
As for the Bunny, you can try to rush pass this level by letting the Bunny keep bouncing, then jump a huge jump and skip apart a large portion of the level.
Runner is an all-rounder for most levels, so you can handle this level fine with him if you have enough skills. Just do high jumps and look for landing place.