Which category signifies an involuntary missing person?

The correct answer refers to a category of involuntary missing persons that directly involves an outside force, specifically abduction or kidnapping. Individuals classified under this category are missing because they have been taken against their will, which constitutes a serious and urgent situation. The involuntary nature of their disappearance necessitates immediate action from law enforcement and emergency responders, as these individuals are often in dangerous circumstances.

In contrast, other categories, such as a person missing in a crowd, a person missing after a natural disaster, or a person temporarily lost, generally relate to circumstances where the individual may not be under duress, but rather lost or separated from others without any implication of malicious intent or criminal activity. Hence, these situations, while they may require assistance, do not carry the same level of urgency and risk as an abduction, distinguishing category C as the most critical among the options provided.