CEC of humus is

Answer: Option D

CEC is cation exchange capability and varies according to the type of soil.
Humus, the end product of decomposed organic matter, has the highest CEC value because organic matter colloids have large quantities of negative charges.
Humus has a CEC two to five times greater than montmorillonite clay and up to 30 times greater than kaolinite clay, so is very important in improving soil fertility.
CEC of humus is 250 - 350.