4. Scenario: Despite many years living in an English-speaking country, a learner still says, “I am agree” and never self-corrects. He uses this form confidently and appears unaware of its inaccuracy. What concept most precisely explains the persistence of this error? (A) Transfer – because the form resembles one from the L1. (B) Interlanguage – because the learner is still developing rules. (C) Output Hypothesis – because production opportunities are lacking. (D) Fossilization – because development has plateaued and the error is resistant to change.