Option 1 -> taciturn means reserved and uncommunicative; speaks very little.
Option 2 -> moody refers to temperamental behavior and unpredictable emotions, unrelated to talkativeness.
Option 3 -> garrulous means excessively talkative; this is actually a synonym of loquacious, not an antonym.
Option 4 -> eloquent describes persuasive and articulate speech quality, not the quantity of speech.
Hence, Option 1: taciturn -> Loquacious means very talkative, while taciturn means habitually silent or reserved, making them perfect antonyms -> correct