What characteristic of transient voltages is noted in their description?

The characteristic of transient voltages that is highlighted in the question is their short duration, which is why the option indicating longer duration is not accurate. Transient voltages are defined by their brief existence; they typically arise due to sudden changes in electrical conditions, such as switching actions or lightning strikes.

The key aspect of transient voltages is their ability to reach high peak values very quickly but only last for a very short time. Therefore, they exhibit a short rise time, which effectively makes transient voltages very brief events characterized by their immediate but temporary impact on the electrical system. Understanding this nature of transient voltages is essential for designing electrical systems and protective measures against such occurrences, emphasizing the importance of mitigating strategies to handle these quick, high-energy events without causing lasting damage.