Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

Which popular Doctor Who villains, it was revealed in 2011, are to be given 'a rest' by scriptwriters?
doctor who

What name is given to the disease whereby parasites can change the behaviour of rats and mice, making them drawn to rather than fearful of the scent of cats?
cat

What is the state capital of California?

california