Answer:
d) They showed that atoms have a dense nucleus.
Step-by-step explanation:
Thomson's model predicted that the atom is composed of negatively charged electrons, which is surrounded by positively charged cloud. This was called Plum pudding model of the atom.
But Rutherford proved it to be incorrect . His gold foil experiment showed that the atom's central part is heavy and positively charged. The deflections of the alpha particles showed that the heavy central region is surrounded by negatively charged particles called electrons.