To determine the correct structure that enabled the construction of the Roman monument in question, we can analyze the responses provided.
The options given are:
- arch
- dome
- flying buttress
- barrel vault
Among these, the Roman architectural innovations are particularly noted for their use of the "arch" and "dome." The arch allowed for the distribution of weight above openings, while the dome provided a way to span large spaces without traditional supports.
The "flying buttress" is more commonly associated with Gothic architecture rather than Roman architecture.
The "barrel vault" is a type of arch built in depth, which can create a tunnel-like passage, but it is essentially a variation of the arch.
If the monument in question prominently features a curved roof or a rounded structure, the correct answer could likely be "dome." However, if it is more about openings and supports in the facade, then it might be "arch."
Without seeing the photo, I would recommend considering which of these characteristics align with the specific Roman monument you are referring to. If the structure is not a church or cathedral (like the Pantheon), I'd lean towards "arch." If it’s emblematic of large open spaces or circular forms, then "dome" would be appropriate.
In the absence of visual confirmation, I would advise selecting "arch" as it is fundamental to many Roman structures.