Plant can assimilate nitrogen in the form of

The correct options are
B ${\mathrm{NO}}_2^{-}$
C ${\mathrm{NO}}_3^{-}$
D ${\mathrm{NH}}_3$
The atmospheric nitrogen ($N_2$) cannot be used by plants. This nitrogen has to be converted to usable forms through various processes. Plants can assimilate nitrogen in the form of ${\mathrm{NO}}_2^{-}$, ${\mathrm{NO}}_3^{-}$, ${\mathrm{NH}}_3$, ${\mathrm{NH}}_4^{+}$.