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

Input: Consider Input: Princess Estelle, Duchess of Ostergotland, granddaughter to King Carl XVI Gustaf, became 2nd in line to what nation's throne when born in 2012?

Output: carl xvi gustaf of sweden

Input: Consider Input: 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?

Output: cat

Input: Consider Input: The film '10 things I hate about you' is based on which Shakespeare play?
Output: 10 things i hate about you