The element that usually does NOT show variable oxidation states is:

Variable oxidation states arise from availability of both 3d and 4s electrons.

| Element | Z | Config | Oxidation States | |---------|---|--------|------------------| | Cu | 29 | [Ar] $3d^{10} 4s^1$ | +1, +2 (variable) | | Ti | 22 | [Ar] $3d^2 4s^2$ | +2, +3, +4 (variable) | | Sc | 21 | [Ar] $3d^1 4s^2$ | +3 only | | V | 23 | [Ar] $3d^3 4s^2$ | +2, +3, +4, +5 (variable) |

Sc loses all 3 electrons to achieve the stable $[\text{Ar}]$ configuration. It cannot show any other positive oxidation state — hence no variable oxidation states.

Answer: Option (3) — Sc