Match the following.

	Column I (Complexes)		Column II (Metals)
(A)	Vitamin B12	(p)	Ti
(B)	Wilkinson catalyst	(q)	Co
(C)	Xiegler-Natta catalyst	(r)	Fe
(D)	Haemoglobin	(s)	Rh

The correct option is A(q), B(s), C(p), D(r).

To match the complexes in Column I with their corresponding central metals in Column II, we can analyze each complex step-by-step:

(A) Vitamin B₁₂: Vitamin B₁₂ (cobalamin) is a water-soluble coordination compound containing a corrin ring coordinated to a central cobalt ion.
Central metal: $\mathrm{Co}$
Thus, (A) matches with (q).

(B) Wilkinson catalyst: Wilkinson's catalyst is a coordination complex used as a catalyst in the homogeneous hydrogenation of alkenes.
Chemical formula: $\mathrm{Rh}\mathrm{Cl}{\left(P{\mathrm{Ph}}_3\right)}_3$
Central metal: $\mathrm{Rh}$
Thus, (B) matches with (s).

(C) Ziegler-Natta catalyst: Ziegler-Natta catalysts are mixtures of transition metal compounds and organometallic compounds, commonly titanium tetrachloride and triethylaluminium, used to polymerize 1-alkenes.
Transition metal compound: $\mathrm{Ti}{\mathrm{Cl}}_4$
Central metal: $\mathrm{Ti}$
Thus, (C) matches with (p).

(D) Haemoglobin: Haemoglobin is a vital iron-containing metalloprotein found in red blood cells that transports oxygen throughout the body.
Central metal in heme groups: $\mathrm{Fe}$
Thus, (D) matches with (r).

Combining these matches, we get:
• (A) → (q)
• (B) → (s)
• (C) → (p)
• (D) → (r)