Concept:The configuration shows a completely filled outermost shell, so the element is chemically stable and has no combining power.Explanation:The configuration is 1s22s22p6.The second shell contains 2+6=8 electrons, which is a full octet.A full octet means the element has a noble-gas configuration.Such an element neither loses, gains, nor shares electrons.Therefore, its combining power or valency is 0.Answer:A. 0