The relative stability of +1 oxidation state follows the order

• A

  $\mathrm{Al}<\mathrm{Ga}<\mathrm{In}<\mathrm{Tl}$

• B

  $\mathrm{Al}>\mathrm{Ga}>\mathrm{In}>\mathrm{Tl}$

• C

  $\mathrm{Al}=\mathrm{Ga}<\mathrm{In}<\mathrm{Tl}$

• D

  $\mathrm{Al}=\mathrm{Ga}>\mathrm{In}>\mathrm{Tl}$