Arrange the following acids in order of the increasing acidity.

A < B < C < D B < C < A < D C < B < D < A C < D < B < A

C < D < B < A

Due to ortho-effect, o-nitrobenzoic acid is the strongest acid. Further since electron-withdrawing groups such as NO2 increase while electron donating groups such as OH decreases the acid strength w.r.t. parent acid, therefore, the overall acidity increases in the order: C < D < B < A