Which of the following describes a violent collapse inward?

The term that describes a violent collapse inward is "implosion." In various contexts, implosion refers to a sudden and dramatic inward failure, where material or structures are crushed from the outside due to atmospheric pressure or an internal reaction. This is commonly seen in demolitions where buildings are brought down in a controlled manner, and all debris falls inward rather than outward, minimizing disruption to the surrounding area.

The other terms do not relate to the concept of a collapse. "Incite" refers to provoking or stirring up an action or emotion, often in a negative context. "Incredulous" describes a state of disbelief, while "incongruous" refers to something that is not in harmony or not consistent with something else. Thus, they do not fit the definition provided by the question.