Humus generally refers to the decomposed organic residues which have undergone a series of degradation and synthesis cycles. The humic substances consist of a series of highly acidic, yellow to black coloured, high molecular weight compounds __________________, which can be separated using different extraction procedures:
A. Hymatomelanic acid & Humin
B. Humic acid & Fulvic acid
C. both A & B
D. None of these
