Final answer:
A compound vault described as having a narrower transverse vault from a higher level, resulting in equally high ridges, is called a Ribbed Vault (option C) . Ribbed vaults are significant in Gothic architecture for their ability to enable greater building height and manage structural forces.
Step-by-step explanation:
A compound vault with a narrower transverse vault that springs from a higher level, creating ridges at the same height, is known as a Ribbed Vault. This architectural feature allowed for greater heights in structures due to its design, where the thrust of the arch is more vertically oriented, distributing the weight more effectively downward than outward. Pointed ribbed groin vaults take this concept further, enabling even more significant height and are a distinguishing feature of Gothic architecture, evolving from earlier forms such as barrel and groin vaults.
In a ribbed vault, the ribs meet in the center of the ceiling of each bay, creating three-dimensional pointed arches. These vaults were essential in maintaining the structural integrity of tall buildings with large stained glass windows by effectively managing the lateral forces exerted by the walls.