Read the excerpt from "the adventure of the mysterious picture."
the expression was that of agony—the agony of intense bodily pain; but a menace scowled upon the brow, and a few sprinklings of blood added to its ghastliness. yet it was not all these characteristics—it was some horror of the mind, some inscrutable antipathy awakened by this picture, which harrowed up my feelings.
what effect does the tone of the excerpt have on the reader?

a. it evokes a sense of anxiety as the narrator observes his surroundings.
b. it evokes a sense of nostalgia as personal experiences are recounted.
c. it fosters confidence that everything will work out fine in the end.
d. it fosters a belief that the narrator is not a reliable reporter.