Final answer:
The correct answer is a Gothic arch, distinguished in Gothic architecture by its pointed shape and concave double curves, which distribute weight down more efficiently than outwards.
Step-by-step explanation:
The shape of a pointed arch, each haunch of which is a double curve with the concave side uppermost, is known as a Gothic arch. This architectural element is essential to the Gothic style of architecture, and it is characterized by its efficiency in more evenly distributing weight downwards rather than outwards. The pointed arch relieved the stress on structural elements, allowing for higher ceilings and thinner walls, compared to the heavier walls required for traditional Roman arches. This change in structure also permitted large windows, making Gothic architecture distinct from the thick-walled Romanesque style.