They are triplets.
or
Because an undocumented worker has been living on his head for the past 2 decades!
or
At the crystal ball.
or
She couldn't control her pupils.
or
None, because people who glow in the dark don't need light bulbs.
Note: Topical to the Chernobyl Reactor disaster of 1984.
or
They can make little things count.
or