Concept:A sill is a horizontal sheet of igneous rock formed when magma is forced between existing rock layers.
Explanation:When magma moves along a bedding plane, it intrudes parallel to the already existing layers of sedimentary rock.
The magma then cools and solidifies as a flat, tabular igneous body.
This feature is called a sill.
A batholith is a huge, deep seated mass of igneous rock, not a thin sheet along a bedding plane.
A dyke cuts across bedding planes in a vertical or steeply inclined manner.
A lava plain is produced by surface lava flows, not by underground intrusion.
Therefore, the only option that matches an intrusion along a bedding plane is a sill.
Answer:D. sill