In which one of the following enzymes, is copper necessarily associated as an activator -

Many enzymes need metal ions as cofactors (activators) for their activity.
Tyrosinase is a copper-containing enzyme. It oxidises the amino acid tyrosine to DOPA and dopaquinone in the pathway of melanin pigment formation (and causes browning of cut fruits).
Carbonic anhydrase requires zinc ($Zn^{2+}$). Lactic dehydrogenase uses the coenzyme NAD, and tryptophanase uses pyridoxal phosphate.
So copper is necessarily associated with tyrosinase.