Question

Humic substances are composed of:

• A. (A), (B) and (D) only
• B. (A), (B) and (C) only
• C. (A), (B), (C) and (D)
• D. (B), (C) and (D) only

Hint:

Remember that humic substances are chemically diverse and include multiple organic compounds such as phenols and acids.

Answer 1

The Correct Option is C

Step 1: Humic substances form from microbial breakdown of lignin and plant residues.
Step 2: Their structure includes phenolic and quinone rings plus carboxylic and fatty acid side chains.
Step 3: All four functional groups are confirmed components, so no option can be excluded.
Step 4: The correct answer is \[ \boxed{\text{(A), (B), (C) and (D)}} \]