18) D

A – Wrong
Chlorine is above zinc and vanadium in the reactivity series. So no displacement.

B – Wrong
Sodium is above zinc and vanadium in the reactivity series. So no displacement.

C – Wrong
Aluminium is above zinc and vanadium in the reactivity series. So no displacement.

D – Correct
Vanadium is above iron in the reactivity series so it cannot be displaced by the iron.

E – Wrong
Magnesium is above zinc and vanadium in the reactivity series. So no displacement.