What type of Roman building was designed to house lower-class citizens and had multiple stories with storefronts?

Insulae are the correct answer because they were a specific type of Roman apartment building designed to accommodate the needs of lower-class citizens. Typically, insulae were multi-storied structures that provided affordable living spaces. The ground floors often featured storefronts or commercial spaces, which allowed for economic activity and convenience for residents. This associated commercial use makes insulae distinct from other types of Roman buildings that served different functions.

For example, curiae were primarily meeting places for the Senate and political gatherings, while basilicas served as public buildings for legal and commercial activities, often with a grand architectural style. Domus referred to the typical single-family homes of the wealthy elite, characterized by a more intimate, enclosed design suitable for higher-ranking citizens. Thus, while other building types played significant roles in Roman architecture and society, insulae were specifically tailored for the residential needs of the urban lower class.