Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.
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Question: area code 701 is an area code for the u.s. state of north dakota.

Answer: area code 701


Question: guido altarelli (july 12, 1941 - september 30, 2015) was an italian theoretical physicist.

Answer: guido altarelli


Question: the mesozoic marine revolution was the great increase in sea-floor predators that ate shellfish.

Answer:
mesozoic marine revolution