The correct option is A Due to poor shieding of 6s2electron by inner d and f electron
Lead · Electron configuration
[Xe]4f145d106s26p2
Due to poor shieding of 6s2electron by inner d and f electron it is difficult to remove 6s2 electron thus they are inert.
Hence, in case of Pb, the +2 oxidation state is more stable than the +4 oxidation state due to inert pair effect.