To determine which detail best expresses a theme of the poem, it would be helpful to understand the overall message or main idea of the poem. However, based on the provided responses, we can analyze each option:
A: "Their eyes are glued to the bright tool." - This could suggest a theme related to technology and distraction.
B: "Stop them and their silly mistakes" - This may suggest a theme about learning from errors or parenting.
C: "Do not leave your kids alone" - This clearly leans toward a theme of supervision or care for children.
D: "They’ll cry if their phone drops or breaks." - This indicates a theme of attachment or dependency on technology.
Depending on the overarching message of the poem, option C: "Do not leave your kids alone" best expresses a theme related to the responsibilities of parenting and the importance of being present for children.