Which materials typically make up the a horizon in soil?

a.) silt and pebbles

b.) sand, silt, and clay

c.) sand, silt, and pebbles

d.) sand, clay, and pebbles

B). Sand, silt and clay

Explanation:

A horizon is a layer that lies parallel to the earth crust. A horizon is a type of horizon which lies below the O horizon. It involves the process of mineralization. It includes fine particles which deposit as a result of weathering process of rocks. Thus it is expected to exhibit sand and silt. The clay is a type of soil that includes organic matter deposit as a result of decay of the plant and animal matter.

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link: