During heat treatment of steel, the hardness of various structures in increasing order is

• A. Martensite, fine pearlite, coarse pearlite, spherodite
• B. Fine pearlite, coarse pearlite, spherodite, martensite
• C. martensite, coarse pearlite, fine pearlite, Spherodite
• D. Spherodite, coarse pearlite, fine pearlite, martensite