With respect to the compounds I - V choose the correct statement(s).

$( A )$

is stabilised by conjugation

$( B )$ Conjugation base of  is  which is an aromatic anion

$( C )$ $- {NO}_{2}$  group is an electron withdrawing group it increases acidic strength of any compound to which
it is added.

$( D )$ The acidic strength order on the basis of ${pK}_{a}$ data $IV > V > I > II > III$ is