It's not FTL communication but the 1/c answer is misleading, it's 1m/c and that's because the bulb is 1m away from the switch, so the information propagates at

It's not FTL communication but the 1/c answer is misleading, it's 1m/c and that's because the bulb is 1m away from the switch, so the information propagates at the speed of light, not faster.