Explanation:

The word 'paucity' means the presence of something only in small or insufficient quantities or amounts; scarcity. The opposite would be a word indicating abundance or plenty. Option (3) 'opulence' refers to great wealth or luxuriousness, implying abundance. Option (1) 'lacuna' means a gap or missing part. Option (2) 'famine' is an extreme scarcity of food. Option (4) 'drought' is a prolonged period of abnormally low rainfall. While 'famine' and 'drought' relate to scarcity, 'opulence' is the direct antonym for a general lack or scarcity.