This is an example of stained glass. The test taker can identify this as the glass decorations are colored to produce depictions of Religious figures and designs.

An apse is a recess in a church where the altar often is; an oculus is not related to glass work, but related to church construction.

Tapestries and mosaics are of different mediums than glass: cloth and tile, respectively.

Image is in the public domain, accessed through Wikipedia Media Commons: https://commons.wikimedia.org/wiki/File:Chartres_-_cath%C3%A9drale_-_rosace_nord.jpg

Ashlar stone is a popular building material in this part of the world. It was cut into huge slabs that were then rested atop one other. It was meant to make the interior and exterior of the space appear seamless and smooth. It is the answer to the Roman's concrete recipe. 

Image adapted from http://www.publicdomainpictures.net/hledej.php?hleda=hagia+sophia+5.

Charlemagne, who was crowned in 774, is responsible for this movement. Though his work was continued and evolved under Otto the Great, Charlemagne is ultimately the originator of the codification of the Christian style. This not only created an aesthetic framework for his empire, but also politically united a continent under a religious artistic philosophy. This question requires students to both know their history and to recognize the deep connection between political power and Christian art, setting the tone for the religiously-rooted power struggles that defined much of the Middle Ages.

The conversion of Constantine changed the Christian religion from an increasingly popular cult within the empire to the declared faith of the most powerful man on Earth. Positions of authority within the church became positions of authority within Roman government (In fact, the contemporary outfits for priests and bishops directly correlate to styles popular with Roman aristocracy), endowing Christians with the financial means to become patrons of the arts. Churches, which became monumental artistic commissions, began to appear all over Europe, as Christianity went from the religion of the marginalized to that of the aristocracy. All of these massive changes would have been impossible without the conversion of Constantine, who effectively turned Romanization into Christianization.  

Rounded arches are perhaps the most recognizable feature of Romanesque architecture-not only because they are recognizably "Roman-like" and are similar to the rounded architectural forms found on classical Roman ruins, but also because they stand in stark contrast to the pointed arches of Gothic architecture.

On the left is Notre Dame de Paris, the seat of the Archbishop of Paris, and on the right is Bath Abbey, a medieval Anglican church. Both of these buildings are prime examples of Gothic architecture, characterized by tall facades, ornate stonework, and large amounts of stained glass.

Rose windows were a common feature of Gothic architecture. The rose window in Notre Dame is one of the most famous.

This church was constructed in 1436, at the height of the Gothic era of architectural construction. It cannot be the fourteenth century (1300s), as that was the Romanesque era, and churches were not being built with this kind of grandeur and detail. This is also, though, not a Renaissance building. You can tell this because the Renaissance boasted a revival of Classical Greek architecture, which is not seen here. The answer must be fifteenth century.

The window is a Rose window, a staple of Romanesque and Gothic architecture, and is very revealing of the time when it appears on a church. These were often made of stained glass, and featured intricate and delicate panes of glass that were in themselves a work of art. The Rose window always sits atop the middle door, and is sometimes flanked by smaller windows on either side. 

The Gothic building tradition is a furthering of the Romanesque, and is more intricate and detailed than Romanesque counterpart buildings. The rose windows are larger and the stained glass more intricate. There was an introduction of the King's Gallery, the row of king sculptures that sit under the rose window. And the facades grew taller and taller until Gothic churches towered over the surrounding city. What didn't change, though, was the Basilican plan.