Among a) Na₂O;    b) MgO;    c) Al₂O₃;     d) P₂O₅   and   e) Cl₂O₇, 

the most basic, most acidic and amphoteric oxide can be

We know that Alkali metal oxide is most basic

Therefore,${\mathrm{Na}}_2\mathrm{O}$ is most basic.

And,Non metallic oxide is acidic.

Therefore, ${\mathrm{Cl}}_2{\mathrm{O}}_7$ is more acidic here.

Here,Aluminium oxide is amphoteric : ${\mathrm{Al}}_2{\mathrm{O}}_3$

Hence, Option(C) is the answer.