Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
Example: Who was the first American President?
Example solution: president of the united states
Example explanation: The question talks about the president of the USA.

Problem: Apart from the USA, Canada and British possessions, which other country from the Americas actively took part in WW2, declaring war on the Axis countries in 1942?
Solution: canada