In the theoretical landscape of first and second language acquisition, Noam Chomsky's nativist paradigm and Stephen Krashen's Monitor Model present foundational hypotheses regarding human linguistic capacity and processing mechanisms. Consider the following four advanced propositions: I. Chomsky's 'poverty of the stimulus' argument posits that children achieve rapid and sophisticated native language mastery despite being exposed to finite, degenerate, and impoverished primary linguistic input, thereby proving the existence of a biologically innate Language Acquisition Device (LAD) containing Universal Grammar (UG). II. Krashen's Acquisition-Learning Hypothesis maintains that explicit formal instruction and conscious rule memorization ('learning') can easily convert into subconscious, spontaneous fluency ('acquisition') at any developmental stage through the direct interface mechanism. III. Krashen's Input Hypothesis (specifically the $i + 1$ formula) asserts that language acquisition occurs when learners are exposed to comprehensible input that is slightly beyond their current level of linguistic competence, mediated by the context and extra-linguistic knowledge. IV. Krashen's Affective Filter Hypothesis suggests that emotional variables such as high anxiety, low self-confidence, and weak motivation raise the affective filter, creating a mental block that prevents incoming comprehensible input from reaching the language acquisition mechanisms. Identify the option that correctly evaluates the theoretical and psycholinguistic validity of propositions I, II, III, and IV according to standard language acquisition theory and Language acquisition principles.