In advanced English morphosyntax and categorical lexical analysis, identifying parts of speech frequently depends on syntactic distribution, valency, and functional shift (zero-derivation) rather than isolated semantic definitions. Consider the following four advanced propositions regarding nouns, pronouns, adjectives, and adverbs: I. A word that functions prototypically as a descriptive adjective in one context (e.g., 'fast' in 'a fast runner') can undergo zero-derivation (functional conversion) to operate as a flat adverb of manner without morphological suffixation (-ly), shifting its modification from a nominal head to a verbal head (e.g., 'She runs very fast'). II. The indefinite pronouns 'one', 'none', and 'some' possess distinct pronominal properties enabling them to head noun phrases independently; however, while 'one' can function as a generic third-person pronoun, a numerical head, or a prop-word substituting for an entire nominal projection, 'none' can govern either singular or plural verb agreement depending on notional concord and semantic context. III. Intensive and reflexive pronouns share identical morphological suffixes ('-self' / '-selves'), but they are syntactically distinct: reflexive pronouns are argument-bound anaphors required by the valency of the governing predicate where the antecedent and the object occupy distinct theta-roles within the same clause, whereas intensive pronouns are non-argument adjuncts (appositive nominal modifiers) that emphasize a referent and can be omitted without violating core clause grammaticality. IV. When an -ing participle form appears pre-nominally preceding a noun, it invariably functions as an attributive adjective if it admits degree modification by intensifying adverbs such as 'very' or 'more' (e.g., 'a very surprising development'), whereas if it retains pure verbal government and takes a direct object complement, it must be analyzed syntactically as a gerundial noun or participial adjunct outside the core adjectival category. Identify the option that correctly evaluates the morphosyntactic, categorical, and theoretical validity of propositions I, II, III, and IV according to standard English grammar.