A: One but don't expect results.
Four. One to hold the lightbulb and three to smoke until the room starts spinning!
Just one. To threaten suicide if you don't change it for him/her.
None. Mice can't change light-bulbs as they are mere rodents without the physical or mental ability to do so. Not to mention it's much safer for them to pilfer food in the dark.
Both of them.
Dago wop wop wop
He pasta away
One costs a lot of money to maintain, keep running, and give you the results you want. The other has four wheels.
They both involve muscles and they both result in a-trophy.
Honestly.
Theeeeeeeeey Never expect the Spanish Inquisition!"
