Argument: public transportation should be closed during the weekend as people like to drive to the city to save time and have flexibility on weekends.
The statement doesn't take the availability of car with all people in account. Or whether the car driving is actually time saving or flexible.
We need to prove the above to hold argument true.

Which of the following must be true based on the claim above?

(A) Driving to the city is much faster than taking the train. (Well, even if this is true, the point says nothing about the flexibility. Does all people have car? Can't determine) (Not Sufficient)

(B) Taking the train is not less expensive than driving a car. (Cost is not a factor in argument) (Not Sufficient)

(C) There are plenty of parking spaces available in the city. (Space is not a matter of discussion in the argument, and even if we consider parking space as the flexibility, it doesn't show everyone requires the parking space. Not all People might own cars) (Not Sufficient)

(D) All metropolitan residents who need to go to the city on weekends have a car at their disposal. (Yes, it does takes into account that all people have a car to commute so closing public transportation for weekend won't effect anyone in any way) (Keep this)

(E) Commuting by train is quicker and more flexible during the work week. (This weakens the argument) (Not Sufficient)

Answer is D

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