instruction:
Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
question:
Which legal drama starring Martin Shaw ran for six series on BBC TV from 2001?
answer:
martin shaw


question:
'Highway 61 Revisited' and 'Blood On The Tracks' were both albums released by which popular singer?
answer:
highway 61 revisited


question:
Which singer had a wardrobe malfunction at the half time show at the 2004 Super Bowl?
answer:

super bowl xxxviii