What do the elements in Group 2 have in common?

They are all alkaline each metals and they each have the same number of valence electrons

Depends on your definition of the modern model. The one created by Neils Bohr differs from the quantum mechanical model.

For the Quantum mechanical model, A is untrue. The QM model is far more accepted than Dalton's because it explained the workings of the atom far better than any before.
For the NB model however, that was not accepted as much because it only worked when working with Hydrogen.

B: No model states that each atom is identical.

C: Dalton's model did NOT recognize particles in the atom, but the NB and QM models do.

D: The reverse is true.

So the answer is C.