When calculating $54\times 96$, Judy fails to write the correct column multiplication. She writes one of the four digits as $7$ and gets a result which has a difference of $1920$ from the correct one. Which digit does she write incorrectly? 
选项为:A:$$5$$  B:$$4$$  C:$$9$$  D:$$6$$  E:It\textquotesingle s impossible to determine.  请回答其中一个选项.