As the number of electrons added to the same principal energy level increases, atomic size generally
C. Decreases.
Vanadium (V)
Vanadium is the only one in the 4th period here so
I think the correct answer would be because copper has a lower activity than hydrogen and cannot replace the bonds in it. Substances that are not oxidizing do not react with copper since the redox potentials are very low. Hope this answers the question.
