Final answer:
The sentence without context clues for 'spectral' being 'ghostly' is '[Prince Prospero's] brow reddened with rage.' because it lacks any ghostly or spectral imagery.
Step-by-step explanation:
The sentence that does NOT contain context clues that spectral means 'ghostly' is: '[Prince Prospero's] brow reddened with rage.'' This sentence does not provide context related to the ghostly or spectral appearance or atmosphere like the others do. The rest of the examples include descriptions that convey a ghostly scene or element such as shrouded figures, pale light, and encounters with apparitions, which serve as context clues.