Mayor: To keep our neighborhoods clean, every street in town will be

Great question! Really demands concentration and focus to get there.

(A) All neighborhoods in which construction is under way are qualified neighborhoods. Incorrect - (What if there is construction but not excessive dirt? Is there such a thing as a clean construction? we don't know..)
(B) All qualified neighborhoods will get their streets swept more than once a month. Incorrect - (Could be correct but What if they don't request it?)
(C) No street will be swept n1ore than once a month unless it is located in a qualified neighborhood. Incorrect. - (could be correct as well, but what if it is in a qualified neighborhood that doesn't request it?)
(D) A qualified neighborhood that requests an interim sweeping will have its streets swept more than once a month. Correct. (Has both necessary actions)
(E) No street in an unqualified neighborhood will be swept more than once a month even if the neighborhood requests it. Incorrect.

Mayor: To keep our neighborhoods clean, every street in town will be swept at least once a month. If a neighborhood needs more frequent sweepings, due to excessive dirt from major construction for example, that neighborhood will be qualified for interim sweepings. All requests for interim sweepings from qualified neighborhoods will be satisfied immediately.

If all of the mayor's statements are true, then which one of the following must also be true?

(A) All neighborhoods in which construction is under way are qualified neighborhoods. - WRONG. Major construction and qualified neighbourhoods with interim requests only qualify.
(B) All qualified neighborhoods will get their streets swept more than once a month. - WRONG. All qualified neighborhoods with interim requests.
(C) No street will be swept n1ore than once a month unless it is located in a qualified neighborhood. - WRONG. Atleast mean once or more than once.
(D) A qualified neighborhood that requests an interim sweeping will have its streets swept more than once a month. - CORRECT. All boxes ticked.
(E) No street in an unqualified neighborhood will be swept more than once a month even if the neighborhood requests it. - WRONG. Beyond scope of the passage.

Only B and D qualify as contenders.

Answer D.