Question

A neon light consists of a glass tube with metal wires at each end. When connected to a high-voltage source, the gas glows.

If a fly lands on the glass tube, what will most likely happen?

The fly will not feel a shock because the glass conducts any free electrons back into the gas.
Electrons will flow directly from the metal wires along the glass and shock the fly.
The fly will not feel a shock because the glass insulates it from the electrons in the gas and the metal.
Electrons that are moving through the gas will be conducted through the glass and shock the fly.

Answer 1

The fly will not feel a shock because the glass insulates it from the electrons in the gas and the metal.

Glass is a good electrical insulator, so the discharge (electrons/ions) stays inside the tube between the electrodes. No significant current can flow through the glass to the fly, so it won't be shocked. (If the tube were cracked or the fly touched an exposed live conductor, a shock would be possible.)