Compound 'A' on chlorination gives compound 'B'. 'B' reacts with alc. KOH gives gas 'C', which decolourises Baeyer reagent and ozonolysis of compound 'C' gives only HCHO compound 'A' is :

Question

( A ) $C_4H_{10}$
( B ) $C_2H_6$
( C ) $C_2H_4$
( D ) $C_2H_{5}Cl$