Final answer:
Milly is the girl in 'maggie and milly and molly and may' who symbolizes tenderheartedness due to her kind treatment of Dorothy, which embodies her caring and compassionate nature.
Step-by-step explanation:
The girl in maggie and milly and molly and may whose response symbolizes her tenderheartedness is Milly. Milly's character is depicted as someone who is sensitive and compassionate, which is exhibited by the fact that she treats Dorothy kindly. This act of kindness reflects her gentle nature and the impact it has on those around her, thereby representing her tenderheartedness in the poem.
The gentle and caring attributes of Milly help us understand the delicate nature of her character, highlighting the theme of compassion in the narrative.