What new Gothic feature appeared in Laon's nave elevation?

A) Rounded nave arcade
B) Gallery of the king
C) Guild windows
D) Triforium

The new Gothic feature that appeared in Laon's nave elevation is the triforium. This architectural element, typically found between the nave arcade and the clerestory in a Gothic cathedral, is a shallow arched gallery within the thickness of an inner wall, above the nave arcade and below the clerestory windows. It was a significant development in Gothic architecture, allowing for a more complex vertical division of the interior space and contributing to the characteristic light and lofty appearance of Gothic cathedrals.