The correct option is A C2H5OH,C2H5ONa,C2H5Cl
The compound A is ethanol C2H5OH. The compound A on treatment with Na gives sodium ethoxide (C2H5ONa) which is compound B.
C2H5OHNa−−→−H2C2H5ONa
The compound A on treatment with PCl5 gives ethyl chloride (C2H5Cl) which is compound C.
C2H5OHPCl5−−−→C2H5Cl+HCl+POCl3
B and C react together to give diethyl ether.
C2H5ONa+C2H5Cl→C2H5OC2H5+NaCl
This reaction is known as Williamson Synthesis.
A, B and C are in the order C2H5OH,C2H5ONa,C2H5Cl
Hence, option (a) is correct.