if a city fails to meet its threshold, what does this mean?

The correct answer would be: it is not economically feasible for its market area to purchase goods and services from it. When a city fails to meet its threshold, it means that the local population or market area does not have enough purchasing power or demand to support the city's businesses and economy. This can lead to economic decline and difficulties in providing essential goods and services to the population.

If a city fails to meet its threshold, it means that it is not economically feasible for its market area to purchase goods and services from it. This indicates that the city's population has grown to such a number that it needed to be considered a global city.

If a city fails to meet its threshold, it means that it is facing certain challenges or limitations that hinder its overall viability. In the context you provided, where the population levels of the area have exceeded its food production for it to be viable, it suggests that the city is unable to sustain itself in terms of meeting the food demands of its residents. This could potentially lead to issues such as food scarcity, increased prices, or a heavy reliance on external food sources.

It's important to note that the other options you mentioned also reflect possible interpretations of a city failing to meet its threshold. For instance, if the population it provides for lives too far away for it to remain relevant in the area, it could suggest that the city's services and resources are no longer accessible or practical for its target population. On the other hand, if the population grew to such a number that it needed to be considered a global city, it means that the city has experienced massive urbanization and is now playing a significant role on the global stage. Lastly, if it is not economically feasible for its market area to purchase goods and services from it, it implies that the city is facing economic challenges that prevent the local market from effectively supporting its businesses and sustaining its economy.

Understanding the specific context and circumstances surrounding the city is crucial in determining the exact meaning of it failing to meet its threshold.