BrCH2-CH2-CHBr-CH3→alc.KOH(excess)/∆ A(major) ;  The compound ‘A’ is

BrCH2−CH2−CHBr−CH3→ alc.KOHCH2=CH−CHBr−CH3→ alc.KOHCH2=CH−CH=CH2A;A conjugated diene is thermodynamiccally most stable.