In advanced English syntax and formal morphosyntax, subject-verb agreement (concord) is governed by strict structural rules involving complex noun phrases, collective nouns, inverted word orders, and quantificational expressions. Consider the following four advanced propositions regarding syntactic concord: I. When a singular subject noun phrase is modified by post-modifier prepositional adjuncts introduced by expressions such as 'along with', 'together with', 'accompanied by', or 'as well as' (e.g., 'The lead investigator, along with her research associates, were presenting the findings at the plenary session'), the verb must agree exclusively with the preceding head noun of the primary noun phrase rather than the noun within the prepositional phrase, rendering the plural verb form ungrammatical. II. When a collective noun denoting a group of individuals (e.g., 'committee', 'jury', 'faculty') acts as the subject of a clause, the choice between singular and plural verb agreement is strictly determined by semantic perspective: singular concord is required when the group is conceptualized as a unified, cohesive entity acting as a single unit, whereas plural concord is mandated when the members of the group are viewed as acting individually or independently. III. In existential and locative inversion constructions initiated by an unstressed introductory 'there' (e.g., 'There remains several critical unresolved issues regarding the implementation of the trade treaty'), the grammatical subject follows the copular verb, and standard English morphosyntax requires the verb to agree in number strictly with this postponed real subject rather than the dummy introductory particle. IV. When compound subjects are linked by correlative conjunctions such as 'either...or' or 'neither...nor', the verb agrees in person and number with the subject noun phrase that is placed closest to the verb according to the proximity rule (e.g., 'Neither the professor nor her graduate students was present at the seminar'). Identify the option that correctly evaluates the grammatical, syntactic, and semantic validity of propositions I, II, III, and IV according to standard English grammar and Agreement (linguistics) principles.