The Romanesque movement inaugurated the great building projects of the church. Though Byzantine, Gothic, and International style movements are likewise responsible for many of Europe's greatest holy buildings, they are all continuations of and evolutions from the Romanesque style. This question requires students to know the chronology of their aesthetic movements.

This is the Hagia Sophia. It is located in Istanbul, on the Black Sea, in Turkey. There are hints of the location of the work in the style of the building. Consider the domed top, mixed with the towers on the corner. It is a unique blending of Greek and Islamic artistic influence.

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

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.