TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: What is the SI unit of capacitance?

SOLUTION: capacitance

PROBLEM: Which alliteratively-named politician served as Abraham Lincoln's Vice-President between 1861 and 1865?

SOLUTION: abraham lincoln

PROBLEM: For which 1988 a cappella song is Bobby McFerrin best known ?

SOLUTION:
bobby mcferrin