Question

the muslim world would be considered which type of region if a geographer was looking solely at religious affiliation?
formal
functional
nodal
perceptual
vernacular

Explanation:

A formal region is defined by a common characteristic, such as religion. The Muslim world shares the common characteristic of Islam as the dominant religion. A functional (or nodal) region is centered around a node or focal point with interactions (e.g., a city - its suburbs, transportation links). A perceptual (or vernacular) region is based on people's feelings and attitudes (e.g., "the South" in some cultural perceptions). Since the question is about a common religious affiliation (a clear - cut characteristic), it fits the formal region definition.

Answer:

Formal