The Direct Method of Language Teaching emphasizes immersion in the target language, meaning that students learn the language naturally by only using the target language (I). This method also relies on repetition of exercises (II) to reinforce learning and develop fluency. Additionally, it focuses on linguistic correctness (III), ensuring that students use proper grammar and pronunciation.
However, problem-solving exercises (IV) are not a defining characteristic of the Direct Method. Problem-solving is more commonly associated with communicative or task-based approaches, rather than the Direct Method, which prioritizes spoken language, repetition, and correction.
Thus, the correct answer is 3 (I, II, and III).