Identify the ortho and para-directing groups towards aromatic electrophilic substitution reactions from the following list

$$\mathrm{\mathop { - OH}\limits_I \mathop { - CN}\limits_{II} \mathop { - C{O_2}H}\limits_{III} \mathop { - OC{H_3}}\limits_{IV} \mathop { - NHCOC{H_3}}\limits_V \mathop { - CHO}\limits_{VI}}$$

The compound or ion which is not aromatic in the following is

Arrange the following in decreasing order of their pK_b values

A. ,$$\mathrm{CH}_3 \mathrm{NH}_2$$

B. $$(\mathrm{CH}_3)_3 \mathrm{~N}$$

C.

D.

Which compound among the following is most reactive towards electrophilic reagents?