Identify each substance and the element associated with it

(A) Ziegler catalyst
Ziegler–Natta catalysts commonly contain titanium compounds such as $\mathrm{TiCl_4}$ along with organoaluminium compounds.
So, $A \to \text{Titanium} \to (IV)$

(B) Blood pigment
The blood pigment is haemoglobin, whose heme group contains iron.
So, $B \to \text{Iron} \to (III)$

(C) Wilkinson catalyst
Wilkinson catalyst is $\mathrm{RhCl(PPh_3)_3}$, which contains rhodium.
So, $C \to \text{Rhodium} \to (I)$

(D) Vitamin $\mathrm{B_{12}}$
Vitamin $\mathrm{B_{12}}$ is a cobalt complex (cyanocobalamin).
So, $D \to \text{Cobalt} \to (II)$

Write the full matching

$A-\mathrm{IV},\quad B-\mathrm{III},\quad C-\mathrm{I},\quad D-\mathrm{II}$

Compare with options

This corresponds to Option A.

Comparison with stored correct answer

Stored correct answer = A
Derived answer = A
Hence, they agree.