Acertain town has a lively, active downtown shopping district, but it is crowded with automobile traffic. some citizens think that the town council should bar traffic from the central street in this shopping district, turning it into a pedestrians only plaza. a town council member makes a speech in favor of the proposal period.

Hello, sorry this is a little late, but hopefully it can help others who visit this question!
I believe the correct answers to your question would be:
Valid Reasons: "Barring motor vehicles from the central area will help reduce air pollution and noise pollution." and "Studies predict that shopping activity in the area will increase if cars are prohibited."
Invalid Reasons: "At a dinner I attended recently, someone complained loudly about the number of cars in the shopping district." and "Many cities of our size have downtowns that are only active during workdays, not on evenings or weekends."
I can confirm these answers are 100% correct!
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