A type of Edge Cities for originally master-planned new townsa.Greenfieldsb.Boomburbsc.Uptowns

The term "Edge Cities" refers to suburban areas that have developed their own economic bases and urban characteristics, often located at the periphery of larger metropolitan areas. Among the options provided:

1. Greenfields: Typically refer to undeveloped land that is usually agricultural or rural, which can be transformed into housing or commercial developments. These areas can sometimes host Edge Cities if they are master-planned.

2. Boomburbs: These are fast-growing suburbs that often arise from the expansion of urban areas. They combine residential, commercial, and recreational spaces. They are indicative of the Edge City phenomenon as they can develop independent economic centers.

3. Uptowns: This term is less commonly used in the context of Edge Cities but can refer to areas in suburban regions that maintain a downtown feel, featuring mixed-use developments and a greater density compared to typical suburbs.

In summary, "Boomburbs" is the most fitting answer as it specifically describes growing suburban areas which align closely with the concept of Edge Cities.