5. Who of all the unknown artists became a legendary figure?

Analysis:

The question asks which unknown artist became a legendary figure. Text D directly addresses this by stating, 'Banksy is probably the most famous English street artist who has already become a legendary figure. It's still true that no one knows the person really is.' This clearly identifies Banksy as the legendary figure who remains largely unknown.

Answer: Banksy is the unknown artist who has become a legendary figure.