A person consumes large quantities of alcohol daily for 20 years. He is physically dependent on alcohol. The drug should  be given to this person is:
Disulfiram is the main drug that is used to make alcohol consumption an unpleasant experience. Disulfiram inhibits aldehyde dehydrogenase, alcohol is not metabolized and acetaldehyde accumulates which produces unpleasant symptoms and patient develops an aversion. All the other given drugs can be used but primarily displaces is tried.
Acamprosate
Disulfiram
Naltrexone
Chlordiazepoxide