Given the task definition and input, reply with output. 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: By 1987, CBS was the only "big three" American TV network to have a co-owned record company. ABC had sold its record division to MCA Records in 1979, and in 1986, NBC's parent company RCA was sold to General Electric, who then sold off all other RCA units, including the record division (which was bought by Ariola Records, later known as BMG).
By 1997, which network was the only "big three" to also have its own record company?