Final answer:
The design of a round window with mullions and traceries extending outward from its center, resembling the petals of a rose, is a characteristic feature of Gothic architecture known as a rose window. These windows often incorporate religious imagery and were particularly prominent during the Rayonnant period of Gothic architecture.
Step-by-step explanation:
The subject of your question is Gothic architecture, specifically the design of a round window with mullions (framing elements) and traceries extending outward from its center in the manner of the petals of a rose. This architectural feature is commonly seen in Gothic cathedrals and is known as a rose window. Rose windows were a typical feature of Gothic architecture but during the Rayonnant period, the stone tracery that made up the stained glass window became thinner and more complex. The design of the rose window often incorporates religious imagery, such as figures of saints and biblical scenes.