Which element is named after the name of a planet?A.Hg B.Po C.Pu D.Ra

The element named after a planet is Plutonium (Pu).

Here is the detailed explanation:

Mercury (Hg): Named after the Roman god Mercury, not the planet itself, although the planet Mercury is also named after the same god.
Polonium (Po): Named after Poland, not after any planet.
Plutonium (Pu): Named after the dwarf planet Pluto. Pluto was once considered a planet, and when plutonium was discovered, it was named after Pluto following a trend of naming elements after celestial bodies (uranium after Uranus, neptunium after Neptune).
Radium (Ra): Named after the Latin word "radius" meaning ray, in reference to its radioactivity, and is not related to any planet.
Thus, the correct answer is C. Pu (Plutonium).