You should always try going to the horse's mouth first - i.e., see if the CBOE has any information posted about the subject.
In this case, the answer isn't as black and white or simple as suggested above.
The following is from the CBOE's Option Corner:
QUESTION:
If an investor purchases a put, the target company files for bankruptcy, and trading is halted in the underlying common stock, what is the mechanism for settling the position? It seems that if the put is in the money it would retain value, but I'm unclear on the settlement mechanism in such a situation.
ANSWER:
The courts, the SEC, another regulatory agency, The Options Clearing Corporation (OCC) or the options markets may impose exercise restrictions. While an American-style option can normally be exercised at any time prior to its expiration, The OCC and the options markets have authority to restrict the exercise of options at certain times in specified circumstances. The option markets often exercise such authority with respect to an option in which trading has been halted. If a restriction on exercise is imposed at a time when trading in the option has also been halted, holders of that option will be locked into their positions until either the exercise restriction or the trading halt has been lifted.
Exercise restrictions imposed by The OCC and the options markets affecting cash-settled options generally cannot be continued in effect beyond the opening of business on the last trading day before their expiration. Such exercise restrictions affecting physical delivery options generally cannot be continued beyond the opening of business on the tenth business day before their expiration, but with one important exception. If The OCC determines that the available supply of a security underlying a physical delivery option appears to be insufficient to permit delivery of the security by the writers of all outstanding calls in the event of exercise, or that foreign government restrictions would prevent or unduly burden the orderly settlement of exercises of foreign currency options, The OCC may indefinitely prohibit the exercise of puts by holders who would be unable to deliver the underlying security. The holder of such a put could lose his entire investment in the option if the prohibition remained in effect until the puts' expiration and the holder was unable either to acquire the underlying interest or to sell his put in the market. The put holder might be unable to do either because the very event that caused The OCC to impose the exercise prohibition (e.g., a suspension of trading in an underlying stock) might not only make it difficult or impossible to obtain the underlying interest, but might also impair the market in options on that interest.
It is also possible that a court, the SEC or another regulatory agency having jurisdiction would impose a restriction that would have the effect of restricting the exercise of an option. In such a case, the option would not be exercisable until the restriction was terminated. In the remote possibility that the restriction were to remain in effect until the expiration of the option-which has never yet occurred-the option would expire worthless, and the holder would lose the entire amount that he paid for the option.