The correct sequence of correct reagents for the following transformation is:-

The starting material is nitrobenzene and the final product is 3-chlorophenol ($$m$$-chlorophenol). Since the chlorine atom and the hydroxyl group are in a $$meta$$ relationship, the chlorination must be carried out while the $$-NO_2$$ group is still present because it is a strong $$meta$$-directing group.

The $$-NO_2$$ group is strongly deactivating and $$meta$$ directing, whereas both the $$-NH_2$$ and $$-OH$$ groups are strongly activating and $$ortho/para$$ directing. Therefore, reducing the nitro group before chlorination would lead predominantly to $$ortho$$ and $$para$$ substituted products rather than the desired $$meta$$ isomer.

The correct sequence is:

• Step 1: $$Cl_2/FeCl_3$$
  Nitrobenzene undergoes electrophilic aromatic substitution, and the $$-NO_2$$ group directs chlorine to the $$meta$$ position, giving $$m$$-chloronitrobenzene.
• Step 2: $$Fe/HCl$$
  The nitro group is reduced to an amino group, producing $$m$$-chloroaniline.
• Step 3: $$NaNO_2,\ HCl,\ 0^\circ\mathrm{C}$$
  The amino group undergoes diazotization to form $$m$$-chlorobenzenediazonium chloride.
• Step 4: $$H_2O/H^+$$ (warm)
  Hydrolysis of the diazonium salt replaces the diazonium group with a hydroxyl group, yielding 3-chlorophenol.

The other sequences are incorrect because:

• Option (A): Reduction occurs before chlorination. The resulting $$-NH_2$$ group is $$ortho/para$$ directing, leading to the wrong products.
• Option (B): Conversion to phenol occurs before chlorination. The $$-OH$$ group is also $$ortho/para$$ directing, so chlorination does not give the required $$meta$$ isomer.
• Option (D): Diazotization is attempted directly on a nitro compound. Only primary aromatic amines undergo diazotization, so the nitro group must first be reduced.

Hence, the correct sequence is Option (C).