Option (1) is correct: Confession made to police officer is always taken as an irrelevant confession.
Option (2) is incorrect: Confession made under promise of secrecy is not always irrelevant.
Option (3) is incorrect: Confession made when the accused was drunk is not always irrelevant.
Option (4) is incorrect: Confession made in consequence of a deception practised on the accused is not always irrelevant.