Answer: C) Sounds of movement can be heard from behind the curtain.
Explanation: In literature, mood is a literary element that evokes certain feelings or vibes in readers through words and descriptions. We can also say that the mood is the emotional setting of the piece or its atmosphere. From the given options, the setting detail that best reveals the mood of suspense in the excerpt, is the corresponding to option C, because it doesn't explain right away, who or what is making the sounds.