What is the CEC of a soil that contains 10% clay. The clay fraction is composed of 50% smectite (CEC=100) and 50% kaolinite (CEC=10)?

A. 55 cmolc/kg

B. 5.5 cmol/kg

C. 10 cmolc/kg

D. None of the listed answers.

E. 68 cmolc/kg