In the sentence Oppressive as nightmare, a formless nameless fatigue, heavier than any burden the slaves of the mines must bear, lies forever at his heart (l.9–12), the simile "Oppressive as nightmare" performs a distinct textual function. It primarily acts as a(n) ______, designed to accentuate the atmosphere of metaphysical oppression and existential suffocation permeating the emperor's condition, rather than to ______ or to ______. Which option correctly completes the blanks in order? Mark the CORRECT alternative.