In advanced English morphosyntax and voice diathesis, active-to-passive voice transformations involve complex operations concerning valency changes, ditransitive object promotion, causative/sensory bare infinitives, and prepositional verbs. Consider the following four advanced propositions regarding active and passive voice conversion: I. When an active clause features a ditransitive verb taking both a direct and an indirect object (e.g., 'The board of directors awarded the senior researcher a prestigious fellowship grant'), standard English grammar permits either object to be promoted to the subject position in the passive voice, yielding either 'The senior researcher was awarded a prestigious fellowship grant by the board of directors' or 'A prestigious fellowship grant was awarded to the senior researcher by the board of directors', both maintaining full syntactic well-formedness. II. When an active sentence contains a complex modal auxiliary construction combined with a progressive aspect (e.g., 'The forensic accountants must be auditing the offshore corporate accounts currently'), standard English passive syntax allows the continuous passive form to be constructed by inserting the gerundial auxiliary 'being' immediately before the past participle, resulting in 'The offshore corporate accounts must be being audited currently by the forensic accountants'. III. In active clauses governed by verbs of sensory perception taking bare infinitives (e.g., 'The night watchman observed the suspicious intruder scale the perimeter fence'), the passive transformation requires the bare infinitive to obligatorily convert into a full to-infinitive (e.g., 'The suspicious intruder was observed to scale the perimeter fence by the night watchman'), recovering the historical marker 'to' that remains unexpressed in the active voice. IV. When an active verb is followed by a fixed prepositional complement that forms a tight lexical unit (e.g., 'The committee laughed at the absurd proposal'), standard English passive conversion requires the preposition to be detached from the verb and placed exclusively at the absolute beginning of the passive sentence rather than remaining adjacent to the lexical verb (e.g., 'At was laughed the absurd proposal by the committee'). 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 English passive voice principles.