In figure 5-2 what is the layer labeled y composed of

In the soil profile, the remains of plants and animals are present in a layer known as the humus layer. The topsoil or the A horizon refers to a zone of leaching and the habitat of various species. The subsoil or the B horizon refers to a zone where the organic matter and soluble salts are leached from the A horizon is accumulated.  

The weathered part of the rock, which produces the parent substance over which a soil establishes makes the C horizon, and the unweathered part of the parent substance forms the D horizon. Thus, from the given diagram it is clear that the layer Y comprises unweathered part of the parent material.  

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]