Arrange the following in decreasing acidic strength.

Acidic nature is more, if the stability of the conjugate base is more. Electron withdrawing groups increases the stability. Nitro group at para position shows $-\mathrm{M}$ effect and meta position it shows $-\mathrm{I}$ effect only.

Methoxy group at meta position shows $-\mathrm{I}$ effect, but effect is Iess than nitro group. Methoxy group at para position shows $+\mathrm{M}$ effect that decreases the acidic nature.