Answer:
Option A
Explanation:
$PCl_{3}$ produces $POCl_{3}$ with the following reagents
$PCl_{5}+SO_{2} \rightarrow POCl_{3}+SOCl_{2}$
$PCl_{5}+H_{2}O \rightarrow POCl_{3}+2HCl$
$ PCl_{5}+H_{2}SO_{4} \rightarrow SO_{2}Cl_{2}+2POCl_{3}+2HCl$
$6 PCl_{5}+P_{4}O_{10} \rightarrow 10 POCl_{3}$