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

[Q]: Physics. What is the SI unit for amount of substance?
[A]: amount of substance


[Q]: Who played Bond Girl Domino Petachi in Never Say Never Again?
[A]: never say never again


[Q]: What was the name of the robot dog that became a regular companion for Doctor Who?
[A]:
doctor who