The Periodic Table: chemical periodicity — practice question

$\text{Ar}$, $\text{Ca}^{2+}$ and $\text{K}^+$ each have the same electron count. In what order do their radii increase?

• AAr → K⁺ → Ca^{2}⁺
• BCa^{2}⁺ → Ar → K⁺
• CCa^{2}⁺ → K⁺ → Ar
• DK⁺ → Ar → Ca^{2}⁺