Which funeral practice involves placing the deceased into the ground?

Burial is the correct answer because it specifically refers to the practice of placing the deceased's body directly into the ground. This method of interment involves digging a grave and placing the body within it, covering it with soil afterward. Burial is one of the oldest and most traditional forms of handling human remains and is commonly associated with grave markers or headstones that commemorate the deceased.

Entombment, on the other hand, involves placing the body in a crypt or mausoleum above ground, and is not the same as burial. Cremation is the process of reducing the body to ashes through burning, which does not involve interring the body in the ground. Inurnment refers to placing cremated remains into an urn, which is also not related to burying a body in the ground. Thus, burial distinctly encompasses the act of laying a body to rest underground, making it the correct choice in this context.