Final answer:
The celestial body related to Proxima Centauri is Alpha Centauri, which is the closest star to the Earth. Proxima Centauri has been the focus of research due to the discovery of exoplanets and the Breakthrough: Starshot project.
Step-by-step explanation:
The celestial body related to Proxima Centauri is Alpha Centauri, option D.
Proxima Centauri is the closest star to the Earth, located in the Alpha Centauri triple star system. In recent years, there has been significant research and discovery of exoplanets around Proxima Centauri, including the planet Proxima b, which is potentially within the habitable zone. Yuri Milner, a Russian-American billionaire, has pledged $100 million towards developing the technology to send miniaturized probes to this star system through the Breakthrough: Starshot project.