Answer:
C. He placed positive material in the atom's center.
Step-by-step explanation:
Ernest Rutherford was a physicist from New Zealand who spent most of his career in England and Canada. Rutherford was an important figure in the history of the discovery of the atom. Rutherford is famous for his gold foil experiment. Based on the results of his experiment, Rutherford concluded that there must be a tiny volume of the atom, containing most of the atom's mass, at the center of the atom. This would have a positive charge, and the rest of the atom must be made of mostly empty space. This positive material in the atom's center is the nucleus.