In the context of second language acquisition and teaching English in a multilingual, diverse classroom, educators frequently encounter complex linguistic barriers, interlanguage fossilization, and error typologies. Consider the following four advanced pedagogical propositions: I. Interlanguage, as conceptualized by Larry Selinker, is a transitory yet systematic linguistic system constructed by an L2 learner that incorporates elements from both the native language (L1) and the target language (L2), governed by its own internal cognitive rules and prone to fossilization if communicative pressure ceases. II. Developmental (or intralingual) errors arise primarily from positive cross-linguistic transfer, where learners successfully accelerate target language acquisition by assuming that all morphological, syntactic, and phonological structures between the L1 and L2 are universally identical. III. Interference (or interlingual) errors occur when habits of the native language are mistakenly transferred to the target language, reflecting negative transfer where L1 constraints override L2 grammatical norms (e.g., direct literal translation of word order or prepositional usage). IV. In modern communicative error analysis frameworks, treating all learner errors as severe behavioral pathology requiring immediate, punitive negative reinforcement is considered pedagogically optimal, as it entirely eradicates interlanguage variability and accelerates creative language mastery. Identify the option that correctly evaluates the theoretical, psycholinguistic, and pedagogical validity of propositions I, II, III, and IV according to standard second language acquisition research and Error analysis (linguistics) principles.