The correct answer is option (a). Parent material
The soil horizon refers to distinct layers of the soils, which are parallel to one another, but have a different composition from the layer present above and below to it.
The soil horizon can be divided into four different layers. First one is organic layer, which is the topmost layer, below this layer second layer of topsoil is present. Below top soil, subsoil is present. Below subsoil, the bottom most horizon parent material is present.
They are both in the same cell
