The correct answer is D. Mica capacitors are characterised by all of the following except low losses.
Mica capacitors are a type of capacitor that uses mica as the dielectric material. Mica is a very stable material with low dielectric loss, making it ideal for use in high-frequency applications. Mica capacitors are also very accurate, with tolerances as low as 0.01%. They are also stable over a wide temperature range, making them ideal for use in harsh environments.
Leakage reactance is the opposition to the flow of alternating current through a capacitor. It is caused by the dielectric material of the capacitor, which has a finite resistance. The leakage reactance of a capacitor is inversely proportional to the frequency of the applied voltage. This means that at high frequencies, the leakage reactance of a capacitor is very low.
The leakage reactance of a mica capacitor is very low, making it ideal for use in high-frequency applications. However, it is not zero, and therefore mica capacitors do have some losses. These losses are typically very small, but they can become significant at high frequencies.
In conclusion, mica capacitors are characterised by all of the following except low losses. They are stable, accurate, and have low leakage reactance. However, they do have some losses, which are typically very small.