which among the following is the best insulator of electricity

a .wood

b .glass

c. dry air

d. cloth

 Glass is the best insulator. Glass is an amorphous (non-crystalline) solid material. Glasses are typically brittle, and often optically transparent. The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, made of about 75% silica (SiO2) plus Na2O, CaO and several minor additives. Often, the term glass is used in a restricted sense to refer to this specific use.

i think it is glass

Glass

a. Wood

i think it's glass......

glass is the best insulator among these

 glass is the best insulator because:

sometimes the wet wood conduct the electricity similarly cloths are wet it act as a conducter

so,glass is the best insulator of electricity

glass

wood

both glass and wood....!