The correct answer is 3. Merrill Swain because The Comprehensible Output Hypothesis was proposed by Merrill Swain in 1985.
Explanation:
Merrill Swain introduced the Comprehensible Output Hypothesis, which suggests that language learners acquire a language not only by understanding input (listening and reading) but also by producing output (speaking and writing).
According to Swain, when learners try to express themselves, they notice gaps in their knowledge and make efforts to modify their language use, leading to language learning.
Why not the other options?
Stephen Krashen – Proposed the Input Hypothesis, which emphasizes comprehensible input (not output) as the key to language acquisition.
M.A.K. Halliday – A linguist known for Systemic Functional Linguistics (SFL), not the Comprehensible Output Hypothesis.
Gertrude Buck – A rhetorician and educator, not known for work in second language acquisition.
Thus, the correct answer is 3. Merrill Swain. ✅