Is it ever okay to follow a question mark with a comma or semi-colon? For example, would any of the following be valid?  

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> The main questions addressed in the literature are: who said it?, what does it mean?, and does it all make sense?
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2

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> The main questions addressed in the literature are, (i) who said it?; (ii) what does it mean?; and (iii) does it all make sense?
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3

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> The main questions addressed in the literature are, "who said it?", "what does it mean?", and "does it all make sense?"
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