Option 1 -> Expert means highly skilled person, which is a synonym of virtuoso, not an antonym.
Option 2 -> Amateur means someone lacking professional skill or expertise, which is the opposite of virtuoso.
Option 3 -> Adept means very skilled or proficient, which is a synonym of virtuoso, not an antonym.
Option 4 -> Irreprochable means faultless or beyond criticism, which relates to moral character rather than skill level.
Hence, Option 2: Amateur -> A virtuoso is a master or highly skilled person, while an amateur is someone who lacks professional expertise or skill, making them perfect antonyms -> correct