Left Panel
The trick is to look at the protons, all other things being equal. The yellow spheres are neutrons we are led to believe. All the diagrams show the same number of electrons(2), so there is no help there.
The upper left
The upper right
The Lower left
All have 2 protons and 2 electrons. <<<< Answer Read the 3 lines above.
The center one has only 1 proton And the lower right has 3. Both of them are wrong.
Right Panel
You have answered this one correctly