3 chains of light globes

the chains are in parallel

they're connected to a battery

the lightglobes in the chains are in series

one of the lightglobes in the 2nd chain breaks


What happens to the brightness of the other two chains?


a) They get brighter
b) They stay the same

I've done it two different ways, and have two seemingly correct ideas working.

What's the answer!

(And reasoning too)