We need to know what will determine if the plan will work or not.
Premise: usage of payphones in Bridgeport has dropped by 90%.

Logical gap: We can assume that the low-income residents do menial jobs for the middle and upper-class residents which means that while in that neighbourhood, they use the payphones available and not the one in their very own neighbourhood.

Explanation: The Bridgeport city council needs what will make residents of Bridgeport demand for payphones. That is why they came up with the plan of removing payphones from the middle and upper-income neighbourhoods and retained the ones in the lower-income neighbourhoods.

Option A - Incorrect
The arguments focus is through the low-income and upper-income neighbourhoods, not directly through people who use payphones, whether they are criminals conducting drug deals or not.

Option B - Incorrect
It is though the low-income residents and the middle- or upper-income residents, and not between the middle- and upper-income residents as stated in this option.

Option C - Incorrect
We are not interested in the number of low-income residents who use cell phones. The argument is concerned about payphones, not cellphones.

Option D - Correct
This should be taken into consideration if the plan will succeed. It is also important to know if the residents will use the payphones retained in the low-income neighbourhoods or if they use the ones in the middle- and upper-income neighbourhoods, which is being removed.

Option E - Incorrect
The argument is not concerned about the revenue to be lost in the city if payphones are eliminated in the city.