What key concept is emphasized by the Input Hypothesis in second language acquisition?

The Input Hypothesis underscores the importance of comprehensible input in the process of second language acquisition. This concept posits that learners acquire language most effectively when they are exposed to language that is slightly beyond their current proficiency level, known as "i+1." The hypothesis emphasizes that for language learning to occur, learners must understand the input they receive. This understanding facilitates communication and helps them internalize the structures and vocabulary of the new language they are learning.

The focus on comprehensible input suggests that exposure to meaningful language interactions plays a crucial role in developing language competence. When learners engage with input that they can understand, they are better able to grasp linguistic structures and use them in appropriate contexts, promoting a more natural acquisition process.

In this context, other options do not directly align with the central tenet of the Input Hypothesis. While writing, physical enactment, and error monitoring may play roles in language teaching and learning, they do not capture the essence of how input serves as a primary mechanism for language acquisition according to this hypothesis.