Detailed Instructions: In this task, you are given a context tweet and an answer. Your job is to generate a question for the given answer based on the given tweet paragraph. Note that your question should be answerable based on the given tweet, and the answer to your question should be the given answer.
Q: Context: Sad to lose Nola @sandiegozoo Now only 3 northern white rhinos remain on our planet. #Nola4Ever #anthropocene. Edward Burtynsky (@edwardburtynsky) November 23, 2015 Answer: three
A:
how many northern white rhinos remain in existence?