The correct option is D should do . . .,"
An ellipsis is a punctuation mark that is used to indicate a missing
word or phrase, without which the sentence is still complete in meaning.
It is represented by three dots '. . .'. In the given sentence, the ellipses has an error, because there are only two dots seen, hence it needs to be changed and option A is incorrect. "Should do . . .," has the correct form of an ellipses, hence option B is correct. "Should do .," has a full stop, it doesn't have an ellipses, hence option C is incorrect. "Should do . . . .," has four dots in its ellipses, whereas it's supposed to have three, hence option D is incorrect.