Final answer:
The zone most likely to have gang members in the concentric zone model is Zone B, or the zone of transition, which is characterized by high population density, transitional housing, and the repurposing of declining areas, conducive to the emergence of gang activities.
Step-by-step explanation:
In the concentric zone model, the zone that is most likely to have gang members is Zone B, also known as the zone of transition. This area is characterized by formerly wealthy homes that have been divided into cheaper apartments to accommodate new immigrant populations.
Zone B is just outside the central business district and is considered a mix of residential and commercial land uses with a high population density. It represents the typical area where newer inhabitants have repurposed declining areas, often pushing out the previous, more affluent residents.