I got you covered.
or
Two… one to tell the engineer to do it, the other to say "I don't know, what do you think?"
or
Billllyuns and billllyuns. Light bulbs are part of the interstellar "goo" that pervades our universe; they are star stuff.
or
A mushroom!
or
Only one, but the bulb has got to really WANT to change.
or
She kept running away from the ball.
or