Correct Answer - B
In the periodic table, inert pair effect increases down the group. So in group `14`, the stability of lower oxidation state of `+2` goes on increasing down the group. This makes `Pb^(2+)` a stable oxidation state.
In `Fe^(2+) (3d^(6))`, the d-orbital is not completely filled. `Ag^(o+)(4d^(10))` is the most stable oxidation state of silver because due to fully filled d-subshell, removal of the second electron is very difficult.
