Final answer:
The theme of the incident involving the roly-poly bug is the consequences of thoughtless actions.
Step-by-step explanation:
The theme of the incident involving the roly-poly bug is 3) The consequences of thoughtless actions. Jem stops Scout from harming the bug, emphasizing that the defenceless bug had done nothing to her. This incident highlights the idea that thoughtless actions or deliberate cruelty can cause harm to innocent creatures. This is similar to the theme that is later exemplified by the death of Tom Robinson.