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.

[EX Q]: the boiling point of a substance is the temperature at which the substance boils, or enters a state of rapid evaporation.
[EX A]: boiling point

[EX Q]: margaret colin (born may 26, 1958) is an american actress.
[EX A]: margaret colin

[EX Q]: altoids are a brand of breath mints and candies that have been sold since the 1800s.
[EX A]:
altoids