The compound A is ethanol \\\\(\\displaystyle C_{2}H_{5}OH\\\\). The compound A on treatment with \\\\(Na\\\\) gives sodium ethoxide \\\\(\\displaystyle (C_{2}H_{5}ONa)\\\\) which is compound B.\\\\(\\displaystyle C_{2}H_{5}OH \\xrightarrow [-H_2]{Na} C_{2}H_{5}ONa\\\\)The compound A on treatment with \\\\(PCl_5\\\\) gives ethyl chloride \\\\(\\displaystyle ( C_{2}H_{5}-Cl)\\\\) which is compound C.\\\\(\\displaystyle C_{2}H_{5}OH \\xrightarrow {PCl_5} C_{2}H_{5}-Cl+HCl+POCl_3\\\\)B and C react together to give diethyl ether.\\\\(\\displaystyle C_{2}H_{5}ONa+C_{2}H_{5}Cl \\rightarrow C_{2}H_{5}OC_{2}H_{5}+NaCl\\\\)A,B and C are in the order \\\\(\\displaystyle C_{2}H_{5}OH, C_{2}H_{5}ONa, C_{2}H_{5}Cl\\\\).Option C is correct.