Reagent ( X ) for the reaction is
\( \xrightarrow[\substack{ CH _{2}}]{ CH _{2}} \xrightarrow{(x)} A \xrightarrow[\text { (Reflux) }]{ Na _{2} SO _{3}} \underset{\substack{ C \\ CH _{2} OH }}{ CH _{2} OH } \)
A \( SeO _{2} \)
B \( \quad Me _{2} SO \)
C \( OsO _{4} \)
D \( RCO _{3} H \)
