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: henan is a province of the people's republic of china.

Answer: henan

Question: plumbaginaceae is a family of flowering plants are about 560 species in 10 genera found all over the world.

Answer: plumbaginaceae

Question: the flag of singapore consists of two horizontal halves, red above white.

Answer:
flag of singapore