The correct answer is A. Paraffin wax.
Dielectric strength is the ability of an insulator to withstand an electric field without breaking down. The higher the dielectric strength, the better the insulator.
Paraffin wax has the least dielectric strength of the given options. This is because paraffin wax is a soft, waxy substance that is easily penetrated by electric fields. When an electric field is applied to paraffin wax, the molecules in the wax align themselves with the field. This alignment creates a dipole moment in the molecules, which can lead to the breakdown of the wax.
Quartz, glass, and air are all better insulators than paraffin wax. This is because they are all harder and less easily penetrated by electric fields. When an electric field is applied to quartz, glass, or air, the molecules in these materials do not align themselves with the field as easily as the molecules in paraffin wax. This makes it more difficult for the electric field to cause the breakdown of these materials.
In conclusion, the correct answer is A. Paraffin wax.