Final answer:
The underlined stage direction in the excerpt from Trifles creates a tense mood in the scene.
Step-by-step explanation:
The underlined stage direction in the excerpt from Trifles affects the mood of the scene by creating a tense mood. The emphasis on the rocker serves as a reminder of where Mrs. Wright calmly sat, which adds to the tension. The characters' reactions to the rocker further contribute to the tense atmosphere.
Learn more about The effect of stage direction on the mood of a scene