$(1)$ In option $B$ AND $C$ there is no transition metals so elimimated
$(2)$ In $\left[ Fe ( CO )_5\right]$ carbon monoxide is a natural ligand, therefore no involvement of $F$ e electrons in complex, $F$ e has zero oxidation state.
(મુક્ત $CO$ માં $C-O$ બંધલંબાઇ $1.128\,\mathop A\limits^o $ છે.
(પરમાણુ ક્રમાંક : $Ti = 22, Cr = 24, Co = 27, Zn = 30$)