instruction:
Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
question:
Which Union leader of the American Civil War gave his name to a tree in California's 'Sequoia National Park'?
answer:
american civil war


question:
What's the name of Doctor Who's home planet ?
answer:
doctor who


question:
Nate Mendel is the bass player in which band?
answer:

nate mendel