The correct option is D All of these
When the reactant is primary alkyl halide and the alc. KOH which is a strong base it prefers E2 elimination rather than substitution. It undergo dehydrohalogenation reaction.
In another reaction, the aq KOH will act as a nucleophile, so the reaction will go only by substitution.
C2H5OHaq.KOH←−−−−−C2H5Brale.KOH−−−−−→CH2=CH2
C2H5OH is functional isomer of CH3OCH3