Answer:
A. The model could not explain how alpha particles could be deflected at large angles.
Explanation:
The plum pudding model of the atom was proposed by J. J Thomson. He suggested that that an atom is made up of dense particles of electrons surrounded by positive charges.
From the Gold foil experiment carried out by Ernest Rutherford, he noticed that the bulk of the alpha particles targeted at the foil passed through and a little fraction was heavily deflected back.
Rutherford then presented his nuclear model from here. He suggested a massive, dense and tiny nucleus where the protons and neutrons are located. The space outside the mass is dominated by orbiting electrons.
Think of it this way,
Mix Iron and sulphur in a bowl. How do you separate them? Use a magnet right. Yes.
Now, mix the iron and sulphur together but know, heat them up. Let them cool for a while. After that, use a magnet to separate. You cant. This is because the compound (FeS) now has a different property from its original components.
Apply this theory onto salts.