Which term describes the overt seizure of individuals to gain publicity or concessions?

The term that best describes the overt seizure of individuals to gain publicity or concessions is hostage-taking. This act typically involves capturing someone and holding them in exchange for certain demands, which can include political, legal, or financial concessions. Hostage-taking is often aimed at attracting media attention to the captor's cause, thereby leveraging the situation for greater visibility and influence.

In contrast, the other terms do not encompass the aspect of gaining concessions through seizing individuals. Kidnapping generally refers to the unlawful taking and carrying away of a person by force or fraud without the intent to use them for political leverage as in hostage situations. Detainment implies a temporary holding of individuals, usually by authority for safety or legal purposes, rather than an overt seizure for publicity. Abduction can refer to the unlawful taking away of a person, but it lacks the specific intent to gain publicity or negotiate concessions, which is central to the definition of hostage-taking.