What architectural feature is characteristic of the Byzantine era, consisting of a dome that rests on four arches?

The correct choice refers to pendentives, which are architectural elements specifically designed to support a dome while allowing it to be placed over a square or polygonal space. In Byzantine architecture, pendentives enable the transition between a dome and the supporting structure below, typically through the use of four arches. This feature not only serves a structural purpose but also creates an expansive, open interior space that is characteristic of Byzantine churches, such as the Hagia Sophia in Istanbul.

Pendentives allow for a unique aesthetic as well, contributing to the overall grandeur of Byzantine religious architecture. They represent a significant advancement in engineering and architectural design by allowing for the creation of larger and more complex domes, which became a hallmark of this era. Therefore, understanding the function and significance of pendentives is crucial for appreciating the innovations in Byzantine architecture.