Answer:). A precise description of what the writer is witnessing when he says that he "could scarcely believe what [his] eyes were seeing".
Step-by-step explanation:
Personal narratives are demonstrated as the narratives written in first person that are primarily intending to relate a personal event or experience of one's life to entertain, inform, convey a message, or merely reiterate an experience.
As per the question, the element that Nick must include next is displayed through option A as it maintains the continuity of the previous description in order to keep the experience or event that is being described in coherence and systematic order. The description of the 'what the writer witnesses when he says 'he could scarcely...seeing' carries the narrative forward in coherence. Thus, option A is the correct answer.