Final answer:
The sentence depicting the House of Usher with its bleak walls and vacant eye-like windows encapsulates the Gothic convention of eerie structures.
Step-by-step explanation:
The sentence from the excerpt from Bram Stoker's Dracula that best represents the Gothic convention of eerie structures is: "I looked upon the scene before me—upon the mere house, and the simple landscape features of the domain—upon the bleak walls upon the vacant eye-like windows—upon a few rank sedges and upon a few white trunks of decayed trees with an utter depression of soul which I can compare to no earthly sensation more properly than to the after-dream of the reveller upon opium the bitter lapse into everyday life-the hideous dropping off of the veil." This sentence vividly depicts the Gothic elements through the description of a dreary and decaying house with vacant eye-like windows and a landscape that induces a deep, oppressive gloom in the narrator.