The input hypothesis includes which key concept as part of Krashen's theory?

• A. Comprehensible output
• B. Negative evidence
• C. Interlanguage fossilization
• D. Comprehensible input

Answer: (D)

Krashen's input hypothesis says language acquisition happens when learners receive comprehensible input that is just beyond their current ability (often described as i+1). The key is that the material must be understandable in context, allowing learners to infer grammar and structure without explicit instruction or forced output. That makes comprehensible input the central idea here—the mechanism Krashen proposed for acquiring a language.

Comprehensible output, while important in other theories, focuses on producing language to aid learning, which is not the mechanism this hypothesis centers on. Negative evidence refers to corrective feedback, which Krashen downplays as essential for acquisition. Interlanguage fossilization describes a separate phenomenon where cemented patterns persist over time and isn’t part of the input-focused process.