Final answer:
The shortest amount of time is the epoch.
Step-by-step explanation:
The SHORTEST amount of time among the options listed is the epoch. Geologic time is divided into various units, starting with eons, which are further subdivided into eras, periods, epochs, and ages. The epoch is the smallest unit of time in this classification system. For example, in the Paleozoic era, there are multiple periods, such as the Cambrian, followed by epochs, such as the Furongian.