Match the following compounds with the oxidation number of the central atom (or specific atom in question):

Compound	Oxidation number
$1$. $C_6H_{12}O_6$ (Carbon)	$a$. $+1$
$2$. $CCl_4$ (Carbon)	$b$. $0$
$3$. $NH_4Cl$ (Nitrogen)	$c$. $+4$
$4$. $Ba(H_2PO_2)_2$ (Phosphorus)	$d$. $-3$

(B) $1$. In $C_6H_{12}O_6$,the average oxidation state of $C$ is $6x + 12(+1) + 6(-2) = 0 \implies 6x = 0 \implies x = 0$.
$2$. In $CCl_4$,$x + 4(-1) = 0 \implies x = +4$.
$3$. In $NH_4Cl$,$x + 4(+1) + (-1) = 0 \implies x + 3 = 0 \implies x = -3$.
$4$. In $Ba(H_2PO_2)_2$,$Ba$ is $+2$. For $(H_2PO_2)^-$,$2(+1) + x + 2(-2) = -1 \implies x - 2 = -1 \implies x = +1$.
Thus,the correct match is $1-b, 2-c, 3-d, 4-a$.