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.

[Q]: plankton are drifting organisms that live in the surface layers of the ocean.
[A]: plankton

[Q]: in law, a conviction is the verdict that results when a court of law finds a defendant guilty of a crime.
[A]: conviction

[Q]: francis warren nicholls, jr. (january 18, 1955 march 31, 2014), better known by his stage name frankie knuckles, was an american dj, record producer, and remixer.
[A]:
frankie knuckles