In advanced English tense-aspect morphology, the interplay between past time reference, habitual iteration, stative semantics, and counterfactual conditional projection exhibits strict grammatical constraints. Consider the following four advanced propositions regarding tenses and their correct usage: I. When expressing a past continuous state or background action that was abruptly interrupted by a punctual, completed event, standard English requires the past continuous tense for the background durative action and the simple past tense for the interrupting event (e.g., "While the astrophysicists were analyzing the telemetry data, a sudden power surge disrupted the mainframe computer"). II. The habitual past modal auxiliary 'would' can freely substitute for the simple past tense or 'used to' with stative verbs denoting permanent existential conditions, abstract possession, or long-term psychological states (e.g., "During her childhood in the remote valley, she *would own* a sprawling Victorian mansion and *would know* every botanical species by heart"). III. In complex past counterfactual conditional clauses (third conditionals), the protasis must utilize the past perfect subjunctive (past perfect tense), while the apodosis must employ the modal auxiliary 'would', 'could', or 'might' followed by the perfect infinitive (have + past participle), as seen in "If the central bank had intervened earlier, the liquidity crisis would have been entirely averted." IV. The historical present tense—often employed in narrative fiction, cinematic synopses, and dramatic commentary to recount past historical events with immediate vividness—can be combined arbitrarily and interchangeably with past progressive and past perfect tenses within the exact same clause without violating temporal sequence or narrative cohesion. 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 Grammatical tense principles.