In advanced English morphosyntax and categorical lexical analysis, identifying parts of speech frequently depends on syntactic distribution, functional shift, and valency rather than rigid semantic labels. Consider the following four advanced propositions regarding nouns, pronouns, adjectives, and adverbs: I. A word that functions prototypically as a descriptive adjective in one syntactic environment (e.g., 'tight' in 'a tight rope') can undergo zero-derivation (functional conversion) to operate as a flat adverb of manner without standard -ly suffixation, preserving its morphological form while modifying a verbal head instead of a nominal head (e.g., 'Hold on tight'). II. The indefinite pronoun 'one' possesses distinct pronominal properties enabling it to head noun phrases independently; however, unlike traditional personal pronouns, 'one' cannot function as a generic third-person pronoun, nor can it serve as a prop-word substituting for an entire nominal projection containing an adjective head (e.g., *'I lost my blue pen and bought a new one'*). III. Reflexive and intensive 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 and Parts of speech principles.