None. The darkness will cause the bulb to change by itself.
or
Three, but they're really only one.
or
Emmental...it's very hol(e)y...
or
Seven. One to change it and the other six to sing about how good the old one was.
or
No thank you, I'm stuffed.
or
He was catching all the chickens!
or
Roberto.
or
Me-ow
or
Because he had no BODY to go with.
or
A Broncosaurus or a Tyrannosaurus Tex.
or