A: None-there weren't any light bulbs in the 13th century.
So it would push back.
Only one; But it takes a WHOLE E.R. room to extract it afterwards. Double joke! "whole... hole." it's a play on words ;)
None. They aren't about to change a bulb when flipping a switch has worked for 15 years.
Trick question, they can't change anything.
Ayatollah you already !