Final answer:
Zaroff's behavior of deliberately stopping his gaze and blowing a smoke ring before walking away suggests that he knows Rainsford is nearby, indicating a foreshadowing of future challenges in their encounter.
Step-by-step explanation:
The actions of Zaroff in the provided excerpt lead to the conclusion that the correct answer is C) Zaroff knows Rainsford is there. Zaroff intentionally stopping his gaze just before reaching Rainsford's location and deliberately blowing a smoke ring into the air indicates a level of confidence and control over the situation. Rather than a sign of defeat or ignorance, this behavior suggests that Zaroff is aware of Rainsford's presence and is taunting him, likely foreshadowing future challenges Rainsford will face in this deadly game of cat and mouse.