You observe that your students need to be exposed to samples of the target language and be encouraged to imitate and respond. Which of the following methods is most suitable for this purpose?

The correct answer is Audio-lingual method.

To understand why this is the most suitable method, let us analyze the core requirements stated in the question and match them with language teaching methodologies:
1. Exposure to samples of the target language: The students need direct input in the form of spoken language patterns.
2. Encouragement to imitate and respond: The students need to practice by repeating (imitating) these patterns and responding through structured drills.

Let us look at the options provided:

1. Audio-lingual method:
This method is based on behaviorist theory, which views language learning as a process of habit formation through conditioning. The key techniques include:
- Drilling and Repetition: Students listen to model dialogues (samples of the target language) and are repeatedly encouraged to imitate (mimic) and respond.
- Pattern Practice: Memorization of structure-based dialogues is highly emphasized to reinforce correct language habits.
This perfectly matches the need for students to be exposed to samples, imitate, and respond.

2. Communicative Language Teaching (CLT):
CLT focuses on interaction, real-life communication, and functional language use. While it involves interaction, its primary goal is not mechanical imitation or repetitive drilling, but rather authentic communication and meaning negotiation.

3. Grammar-Translation Method:
This traditional method focuses on reading, writing, translating texts, and learning explicit grammar rules. It features very little oral exposure, imitation, or active spoken response in the target language.

4. Direct Method:
The Direct Method teaches language directly without translation, using target language communication exclusively. While it involves active participation, it focuses more on association of ideas and demonstrations rather than systematic, structured imitation/drilling (like the listen-and-repeat drills characteristic of the Audio-lingual method).

Therefore, the method specifically designed for systematic exposure to language samples followed by imitation (drilling) and response is the Audio-lingual method.