GMAT Sentence Correction (SC) | Re: THe Roman continued to use lead vessels in making wine even

THe Roman continued to use lead vessels in making wine even after they had been warned that they might poison themselves by doing it.

a)

b) it might be poisonous for them to do that.

c) Doing so might be poisonous for themselves

d) they might be poisoning themselves by doing so.

e) it could be poisonous for them to do that.