The main responsibility of a language teacher as a facilitator is to create a number of opportunities for the learners to use the language meaningfully. This approach focuses on enhancing the learners' language skills through active participation and engagement rather than simply providing information and explanations. Let's break down why option 'D' is the correct answer.

Creating Opportunities for Language Use
As a facilitator, the language teacher's primary goal is to provide learners with ample opportunities to practice and apply the language in meaningful contexts. This involves designing activities and tasks that encourage learners to actively use the language, such as conversations, role-plays, group discussions, debates, and presentations. By engaging in such activities, learners can develop their speaking, listening, reading, and writing skills effectively.

Promoting Meaningful Language Learning
The facilitator's role is to ensure that learners understand the purpose and relevance of learning a language. They should create a positive and supportive learning environment where learners feel motivated and encouraged to participate actively. By connecting language learning to real-life situations and personal experiences, the teacher helps learners see the practical value of the language and its relevance in their lives.

Encouraging Communication and Collaboration
In order to facilitate language learning, the teacher should foster a classroom environment that promotes communication and collaboration among learners. This can be achieved through pair work, group activities, and projects that require learners to interact and work together. By engaging in meaningful conversations and collaborative tasks, learners can develop their language skills while also building their confidence and interpersonal skills.

Providing Feedback and Guidance
As a facilitator, the teacher should provide constructive feedback and guidance to learners. This involves giving feedback on their language use, pronunciation, grammar, and vocabulary, as well as guiding them on how to improve their language skills. The teacher should also encourage self-reflection and self-assessment, helping learners identify their strengths and areas for improvement.

In conclusion, the main responsibility of a language teacher as a facilitator is to create a variety of opportunities for learners to use the language meaningfully. This approach focuses on active participation, meaningful communication, and collaborative learning, ultimately leading to effective language acquisition and development.