Quick please

So S B Three identical lightbulbs are connected in parallel to a constant voltage power supply. Initially, switch S1 is closed and the other two switches open. When the other two switches, S2 and S3, are closed, the brightness of the first light bulb B1 O will depend on how long the switches are on. O will be less. O will be unchanged. O cannot be predicted without knowledge of V and resistance. O will be more