Glycogen debranching

Glycogen phosphorylase stops cleaving when it is four glucose residues from a branch point. Which enzyme activity allows glycogen breakdown to continue?

1. ABranching enzyme, which forms new α(1→6) bonds✕
2. BDebranching enzyme, which moves glucose residues and hydrolyzes the α(1→6) bond✕
3. CGlycogen synthase, which removes branch residues✕
4. DPhosphoglucomutase, which cleaves α(1→6) bonds✕