A third group is least likely to enter between two groups in the meta relationship. This is the result of steric hindrance and increases in importance with the size of the groups on the ring and with the size of the attacking species.
When a Meat-directing group is meta to an ortho-para directing group, the incoming group primarily goes ortho th the meta directing group rather than para.
Chlorination of `m-`chloro nitro benzene gives :

Options

A.
B.
C.
D.

Answer

B