To assure that the unions do not make a counter offer

You do not need to underline To assure and with outstanding benefits since they remain same in all the options.

Now, the explanation:

A. The modifier To assure that the unions do not make a counter offer may seem to wrongly refer to workers. However strictly speaking this is not a correct explanation !! Infinitives of purpose CAN be used along with passive voice, even though the person whose intention is expressed is not mentioned in the sentence. For example:
To keep the room warm, the window was closed. Correct. Just make sure that the person (whosoever be it) closed the window on purpose.
However as Chetan pointed out the indirect object of assure is missing, and hence it is unclear who assured whom. (who and whom both missing).

B. The usage of assure is as follows:
To assure someone(indirect object) something (direct object). Here that the unions do not make a counter offer is the direct object of assure. However omitting that wrongly indicates that the unions is the indirect object of assure.
The verb have does not agree with the subject board.

C. The usage of assure is as folows:
To assure someone(indirect object) something (direct object). Here that the unions do not make a counter offer is the direct object of assure. However omitting that wrongly indicates that the unions is the indirect object of assure.

D. Correct. .. eliminates all errors above.

E. The verb have does not agree with the subject board.

Hi chetan2u, I took this sentence from Magoosh GMAT idioms book and added errors around it.

missing noun regarding who made the offer to workers with outstanding benefits.Use of that is correct So correct ans seems to be option D

P.S. This occurs to me as a poorly worded question

"the board of the parent organisations" is nowhere in the original sentence. :/
Even option A looks correct, as there's nothing wrong with modifier rule as someone has pointed already in this thread.

Request experts to please throw some light on this.

A) To assure that the unions do not make a counter offer, workers have been provided with outstanding benefits. -- passive voice. keep

B) To assure the unions do not make a counter offer, the board of the parent organisations have provided workers with outstanding benefits. -- SV error. Board is singular, needs "has"

C) To assure the unions do not make a counter offer, the board of the parent organisations has provided workers with outstanding benefits. -- Incorrect. "assure" requires a "that"

D) To assure that the unions do not make a counter offer, the board of the parent organisations has provided workers with outstanding benefits. -- Correct.

E) To assure that the unions do not make a counter offer, the board of the parent organisations have provided workers with outstanding benefits. -- Incorrect. "have".

Request experts to help here please.

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