The consistency index of soil is defined as the ratio of:

• A. Subtraction of natural water content from liquid limit to the plasticity index of the soil
• B. Subtraction of plastic limit from natural water content to the plasticity index of soil
• C. Summation of natural water content of a soil plus its plastic limit to the plasticity index of the soil
• D. Summation of liquid limit and natural water content to the plasticity index of soil