Most recovering heroin addicts seek to be free of drug

Option A: Wrong
This sentence makes sense but not to the mode of answering this particular question because it does not differ from the underlined expression in its original form.

Option B: Wrong
This statement is ambiguously specified. ''Both'' means more than one thing is being talked about, it is a connector. likewise, ''also'' means ''in addition to'' previous mentions; it makes the sentence a bogus and complex one.

Option C: Right
'both of drug dependency and also from prejudicial'. It appears the most logical of all the options. The use of the preposition ''form'' suitably follows from the word ''prejudicial'' which the patient is being freed 'from'. It accounts well for the mood of the original statement.

Option D: Wrong
This statement is a negative, contradictory one which appears or already have changed the meaning of the original statement. The use of ''but'' here means a classic deviation which contrasts with the use of ''both'' which seeks to conjoin.

Option E: Wrong
''Both'' seeks to add an extra item to something. So, it doesn't follow that ''as well'' would be appropriately fitting here because it means ''in addition to''. It compliancates the mind of the reader and put the writer on a bad shape grammatically.