What characteristic must a polarized capacitor have?

A polarized capacitor is specifically designed to operate with a designated positive and negative terminal, which means it must be connected in a circuit with the correct polarity. If a polarized capacitor is connected incorrectly, meaning the positive lead is connected to a negative voltage or vice versa, it can lead to catastrophic failure. This failure might include the capacitor overheating, leaking, or even exploding due to excessive internal pressure from improper voltage application. Therefore, the key characteristic of a polarized capacitor is that it must always be connected according to its specified polarity to function correctly and safely.

In contrast, options related to resistance to high temperatures or symmetrical design do not apply specifically to the operation of polarized capacitors. Additionally, the notion that a polarized capacitor can be connected in any way contradicts the fundamental requirement for proper polarity which is critical for its safe and effective use.