Read the excerpt below and answer the question.

I was staring at the door, making it out in my mind rather than seeing it, in the dark. I lay quite still—a victim already—but the arrhythmia of my heart was fleeing, knocking this way and that against its body-cage. How finely tuned the senses are, just out of rest, sleep! I could never listen intently as that in the distractions of the day; I was reading every faintest sound, identifying and classifying its possible threat.

Identify the tone of this excerpt from the opening of Nadine Gordimer’s “Once Upon a Time.”
A. ominous
B. flat
C. peaceful
D. angry