Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
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Question: On November 22, 1986, which boxer became the youngest WBC Heavyweight champion, at age 20 years, 4 months, when he scored a TKO over Trevor Berbick in the second round?

Answer: boxing


Question: Which engineer built the Menai Suspension Bridge and the Caledonian Canal?

Answer: menai suspension bridge


Question: What popular sci-fi creations were described by Dr Who's executive producer in 2011 as ...the most reliably defeatable enemies in the universe... ?

Answer:
doctor who