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: alphonse laveran (charles louis alphonse laveran, 18 june 1845 – 18 may 1922) was a french military doctor.

Answer: alphonse laveran


Question: plankton are drifting organisms that live in the surface layers of the ocean.

Answer: plankton


Question: a down payment is the amount that being paid first at the beginning of any business transaction and settle the remaining payment through installments.

Answer:
down payment