The correct answer is not provided in the question. The world`s first `negative emission carbon-capture plant` does not have a specific country mentioned. It is important to note that this technology is still being developed and tested in multiple countries around the world. While Iceland, Germany, Japan, and China are all countries that are actively working towards carbon capture and negative emission solutions, it cannot be determined from the information given which country the first operational plant is located in. It is crucial to stay updated with advancements and announcements in the field of carbon capture to identify the specific country where this milestone is achieved.