Which of the following capacitors preferred for high frequency circuits ?

The correct answer is C. Mica capacitor.

Mica capacitors are preferred for high frequency circuits because they have a very low loss tangent, which means that they do not dissipate much energy as heat. They also have a high dielectric constant, which means that they can store a lot of charge for their size.

Air capacitors are not very good for high frequency circuits because they have a high loss tangent. Electrolytic capacitors are also not very good for high frequency circuits because they have a relatively low dielectric constant and they can be damaged by high voltages.

Here is a brief explanation of each option:

• Air capacitors are made up of two metal plates separated by a layer of air. They are very simple and inexpensive to make, but they have a high loss tangent, which means that they dissipate a lot of energy as heat. This makes them unsuitable for high frequency circuits.
• Electrolytic capacitors are made up of a metal anode, an oxide dielectric, and a metal cathode. They have a high capacitance for their size, but they have a relatively low dielectric constant and they can be damaged by high voltages. This makes them unsuitable for high frequency circuits.
• Mica capacitors are made up of a thin sheet of mica, which is a naturally occurring mineral. Mica has a very low loss tangent and a high dielectric constant, which makes it ideal for high frequency circuits.