Bomb Optimization

DRDO has recently invented bombs which create a crater on the ground where they are detonated but the nice part is that their impact radius can be modified just before detonating them i.e. radius $r$ of the crater made by the explosion can be controlled just before the bomb explodes. Bombs are still in testing phase, so you're given three bombs ,bomb $A$, $B$ and $C$ and the respective co-ordin