The dark plains of the Moon known as maria are best described as which?

• A. Highland regions
• B. Craters filled with dust
• C. Volcanic cones
• D. Vast lava-flooded basins

Answer: (D)

Maria are large, dark plains on the Moon formed by ancient volcanic activity. They are vast basaltic lava plains that flooded and filled large impact basins, then cooled into smooth surfaces. The dark color comes from basalt rock, which is darker than the Moon’s lighter highland crust. These plains are mainly on the near side and are younger than the heavily cratered highlands, which is why they appear as broad, relatively flat areas rather than rugged terrain.

So, the dark plains are best described as vast lava-flooded basins. They’re not simply highland regions, not merely craters filled with dust, and not individual volcanic cones.