The passage specifically mentions the sounds of children playing. Thus, the correct answer is (b) Playing.
Emily's feelings are conveyed through her appreciation of the park and the peaceful description of the scene.
The detail (d) "Emily felt peaceful and content" directly expresses her emotion, while other details describe the setting but do not explicitly state her feelings.
The passage describes the park as having cheerful sounds and quiet beauty, indicating a (b) Quiet and serene atmosphere.
The passage mentions the sun setting, which indicates that the weather was clear and sunny.