@TanYongBoon You should maybe just analyze this explicitly with Clar's rule - pretty much what you did. You shouldn't equalize aromatic stabilisation with numbers of electrons.
Reactions involving strong electrophiles (nitration) are
said to be governed
by
Inductive effects thus the order of nitration is
D>C>B>A
2.Chlorination is not a strong electrophile so it is said the be governed by hyper conjugation.
...