Sentence:The [e1]puzzle[/e1] gradually emerged from a long-term [e2]study[/e2] of the properties of asteroids carried out by MIT professor of planetary science Richard Binzel and his students, along with postdoctoral researcher P. Vernazza, who is now with the European Space Agency, and A.T. Tokunaga, director of the University of Hawaii's Institute of Astronomy.
 e1: puzzle. 
 e2 : study.
Answer: Entity-Origin(e1,e2)