Read the excerpt from "rhapsody on a windy night." twelve o'clock. along the reaches of the street held in a lunar synthesis, whispering lunar incantations dissolve the floors of memory and all its clear relations, its divisions and precisions, every street lamp that i pass beats like a fatalistic drum, and through the spaces of the dark midnight shakes the memory as a madman shakes a dead geranium. which phrase from the excerpt best indicates that the narrator is lost in thought?

 When the narrator mentions that "Whispering lunar incantations/ Dissolve the floors of memory/ and all its clear relations,/ Its divisions and precisions", we can deduce that he is lost in thought, because some key words indicate so. The floor of his memory and its divisions and precisions are all dissolved by the incantations, meaning they are no more, they disappeared. But, as he continues, a single phrase "Midnight shakes the memory" confirms more clearly the narrator is lost in thought.

"a" because he is appealing to logic as oppose to appealing to the audience's emotions.