BASES -
If 1 then BU--- since B---- and BUSES=2.
If 3 then BAS--- since B---- SLEEP, STEPS=0.
If 2 then B-S--- since exactly one of -AS-- has to be true from B---- and SLEEP, STEPS=0 but since BUSES=2 exactly one of -US--- has to be true. And it can't be both A and U on the same spot, so S has got to be it.