You will be given a definition of a task first, then some input of the task.
This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.

Passage: On November 30, 2010, CBC's senior director of regulatory affairs issued a letter to the CRTC regarding CBC's plans for transitioning to digital. The letter states, "CBC/Radio-Canada will not be converting its analogue retransmitters in mandatory markets to digital after August 31, 2011." On December 16, 2010, some months after the CRTC issued a bulletin reminding broadcasters that analog transmitters had to be shut off by the deadline in mandatory markets, the CBC revised the documents accompanying its August 6, 2010 news release to state that it had the money for and is striving to transition all 27 transmitters by August 31, 2011.
Output:
The senior director of the CRTC issued a letter to address what concern in November of 2010?