Concept used

Variable oxidation state is a common property of transition elements because both $ns$ and $(n-1)d$ electrons can participate in bonding.

However, some elements show only one common oxidation state because they attain a particularly stable configuration.

Check each option

A: Vanadium $(\mathrm{V})$

Vanadium shows several oxidation states: $+2, +3, +4, +5$ So, it does show variable oxidation states.

B: Copper $(\mathrm{Cu})$

Copper commonly shows: $+1, +2$ Hence, it does show variable oxidation states.

C: Scandium $(\mathrm{Sc})$

Scandium has electronic configuration: $[\mathrm{Ar}]\,3d^1 4s^2$ It most commonly forms: $\mathrm{Sc}^{3+} : [\mathrm{Ar}]$ This noble gas configuration is very stable, so scandium usually shows only the $+3$ oxidation state.

Therefore, scandium usually does NOT show variable oxidation states.

D: Titanium $(\mathrm{Ti})$

Titanium shows multiple oxidation states such as: $+2, +3, +4$ So, it does show variable oxidation states.

Conclusion

The element that usually does not show variable oxidation states is: $\boxed{\mathrm{Sc}}$

Compare with stored answer

Stored correct answer: C

Derived answer: C

So the derived answer agrees with the stored answer.