Statement I: Aluminium is amphoteric in nature. 

Statement II: Aluminium dissolves in $\mathrm{dil}. \mathrm{HCl}$ as well as in aqueous solution of $\mathrm{NaOH}$ evolving ${\mathrm{H}}_2$.

An amphoteric substance is one that can act as either an acid or a base, depending on the medium.

(1) If both Statement I and Statement Il are true and Statement II is the correct explanation of Statement I.

An amphoteric compound is a molecule or ion that can react both as an acid and as a base. Aluminium is amphoteric in nature as it gets dissolved in $\mathrm{dil}. \mathrm{HCl}$ as well as in aqueous solution of $\mathrm{NaOH}$ evolving ${\mathrm{H}}_2$ . Hence, we can say that Statement II is the correct explanation of Statement I.

(2) If both Statement I and Statement II are true but Statement II is not the correct explanation for Statement I

Aluminium is termed as an amphoteric as it shows chemical reactivity with both acids as well as bases. In some cases, it behaves as a basic oxide and reacts with an acid to form salt and water whereas in other cases, it reacts with a base to produce the same.

Hence this option is incorrect.

(3) If Statement I is true but Statement II is false.

Both the statements are true as amphoteric means reaction with both acid and base . the statement II explains the same as said ,Aluminium dissolves in $\mathrm{dil}. \mathrm{HCl}$ as well as in aqueous solution of $\mathrm{NaOH}$ evolving ${\mathrm{H}}_2$ . Hence this option is incorrect.

(4) If Statement I is false and Statement II is true.

The statement II explains that Aluminium dissolves in $\mathrm{dil}. \mathrm{HCl}$ as well as in aqueous solution of $\mathrm{NaOH}$ evolving ${\mathrm{H}}_2$ . Aluminium is amphoteric in nature, this is also a true statement. According to it, statement II cannot be false. Hence this option is incorrect.

Therefore, the correct option is 1.