In advanced English morphosyntax and reported speech, transforming complex direct discourse involving mixed sentence types, conditional subjunctive embeddings, and dual reporting verbs demands meticulous adherence to backshifting rules and complementizer selection. Consider the following four advanced propositions regarding indirect speech: I. When a direct speech sentence features a past counterfactual conditional clause (e.g., The lead investigator remarked, "If the financial audit had been completed earlier, we would have detected the fraud"), both the past perfect subjunctive in the protasis and the modal perfect construction in the apodosis resist structural backshifting and remain unchanged in indirect conversion due to their fixed irrealis modal semantics. II. When direct speech reports an ongoing historical fact or a timeless gnomic universal truth (e.g., The physics professor stated, "Electromagnetic radiation propagates through a vacuum at a constant velocity approximately equal to 299,792 kilometers per second"), the past tense reporting verb mandates the backshifting of the embedded present simple verb ('propagates') to the past simple ('propagated') to satisfy strict sequence of tense constraints. III. In indirect wh-interrogative transformations where the direct question already embeds a relative clause containing a past-tense verb (e.g., The detective asked, "Whose forged signatures which were discovered in the vault required immediate forensic analysis?"), the word order of the primary clause must shift from direct subject-auxiliary inversion to standard declarative word order while retaining the embedded relative clause structure intact. IV. When direct speech combines an exclamatory exclamation with a vocative noun phrase and an emotional interjection (e.g., The commander shouted, "Alas, soldiers, we are completely trapped behind enemy lines!"), the indirect speech conversion must replace the interjection and vocative with an appropriate matrix reporting verb phrase expressing emotion (e.g., exclaiming sorrowfully to the soldiers), eliminate the exclamatory punctuation marker, and backshift the present tense to the past tense. 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 Indirect speech principles.