Final answer:
Soupy Sue claims to have an escape plan that would prevent a certain action.
Step-by-step explanation:
The answer to the question is c) An escape plan. Soupy Sue claims to have an escape plan that would prevent a certain action. This is indicated in the provided text where it mentions 'He has plans. He has learned things that mean the fall of Richmond if he escapes.' There is no mention of Soupy Sue having Cladwell's daughter, a secret weapon, or a powerful ally.