Final answer:
The 'stately "throne room"' is the architectural element commonly found in the Megaron at Mycenae, Pylos, and Tiryns, defined by a large reception hall with a central hearth bordered by four columns.
Step-by-step explanation:
The architectural element commonly found in the Megaron of Mycenae, Pylos, and Tiryns is the stately "throne room" or C option from the provided choices. This central feature of a Mycenaean citadel site typically included a large reception hall, a throne placed against the right wall, and a central hearth bordered by four wooden columns that supported the roof.
The hearth, which was a key feature, was vented through an oculus in the roof above it. These columns were significant in the design of the majestic Megaron, which later influenced the basic shape of Greek temples.