This is related to both #354240: Answers in select fields not accepted if questions contain apostrophe AND the field accepts multiple answers and #328528: Checkbox values in form_state rendered incorectly., basically when put together, the problem still exists. If a question contains a quote AND you use the back button, the question with the quote looses it's value when you return to that page.
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Comment #1
quicksketchI fixed this in the 3.x version as part of #354240: Answers in select fields not accepted if questions contain apostrophe AND the field accepts multiple answers.