Which of the following theories are associated with humus formation?
1. Polyphenol theory 2. Lignin-protein theory 3. Chemiosmosis theory 4. Sugar-amine condensation theory
Choose the correct answer from the options given below:

Correct option is A

The theories associated with humus formation include:
• Polyphenol theory
• Lignin-protein theory
• Sugar-amine condensation theory
These theories explain the complex processes involved in the stabilization and formation of humus. Chemiosmosis theory is related to ATP synthesis in biological systems and not to humus.
Hence, the correct combination is (A), (B), and (D) only.