Questions

All  are  correct  except  B  as  Aridisol is just like sand like soil as in Arid region  e.g.  In  Rajasthan,  so  there will be very less amount of organic matter.

Leukocyte, commonly known as a white blood cell (WBC), is a major component in protecting the body against invading microorganisms and body cells with mutated DNA, and they clean up debris. 

B Lymphocyte also called as B-Cells or plasma cells produces the antibodies or immunoglobulins that bind to specific foreign or abnormal components of plasma membranes. This is also referred to as humoral (body fluid) immunity.