In the theoretical frameworks of second language acquisition, Noam Chomsky's nativist theory and Stephen Krashen's Monitor Model offer distinct explanations for how human beings process and internalize language. Consider the following four advanced propositions regarding these linguistic models: I. Chomsky's hypothesis posits that human infants are born with an innate Language Acquisition Device (LAD) containing universal grammar, enabling them to deduce structural rules from primary linguistic input without requiring explicit formal instruction or negative evidence. II. Krashen's Acquisition-Learning Hypothesis asserts that 'acquisition' is a subconscious process resulting from natural communication—identical to the way children master their first language—whereas 'learning' is a conscious process resulting from formal instruction in rules. III. According to Krashen's Affective Filter Hypothesis, high levels of anxiety, low self-confidence, or excessive self-absorption raise the affective filter, thereby facilitating a faster intake and subconscious integration of complex grammatical structures into the learner's developing interlanguage. IV. Krashen's Input Hypothesis (the $i+1$ formula) claims that language acquisition occurs when learners comprehend linguistic input that is slightly beyond their current level of competence, facilitated by the context and extralinguistic cues. Identify the option that correctly evaluates the theoretical validity of propositions I, II, III, and IV according to second language acquisition pedagogy and Second-language acquisition principles.