To determine which inference would be invalid based on the excerpt from "Nelly Bly Undercover," it would be helpful to know the specific options you're considering. However, generally speaking, an invalid inference would be a conclusion that is not supported by the text, misinterprets Nelly Bly's intentions or actions, or draws a conclusion that goes beyond the information provided in the text.
If you provide the specific options or statements you want to evaluate, I can help identify which one would be considered an invalid inference.