Explanation:

The original sentence is erroneous.

Reason: The word ‘urban’ means ‘relating to or characteristic of a town or city’ and is unsuitable in this sentence. The correct word to be used here is ‘urbane’ which means ‘courteous and refined in manner’. Hence ‘urbane’ should be used in place of ‘urban’ to make the sentence grammatically correct.

Among the given choices, only option D replaces the given bold part most appropriately.

The sentence after replacement becomes:

Mr. Tharoor’s urbane manners charm friends and enemies alike.

Option D is hence the correct answer.