Concept:A sill is a tabular igneous intrusion that forms parallel to the existing rock layers, giving it a horizontal or gently inclined orientation.
Explanation:When magma is injected between layers of sedimentary rock, it spreads out in a relatively thin, flat sheet.
Because this sheet follows the bedding planes of the surrounding rock, it lies horizontally or nearly so.
By contrast, a dyke cuts across the rock layers and is usually vertical or steeply inclined.
A laccolith is a concordant, dome-shaped intrusion that pushes the overlying strata upward, so it is not simply a flat horizontal sheet.
A batholith is an enormous, irregularly shaped mass of igneous rock that does not have a consistent horizontal form.
Among the given options, only the sill is characteristically a horizontally inclined igneous intrusion.
Answer:A. Sill