Pick up the correct statement from the following:

• The range of water content between the liquid limit and plastic limit, is called plasticity index.
• The ratio of the liquid limit minus the natural water content to the plasticity index of soils, is called consistency index
• The ratio of natural water content minus its plastic limit to its plasticity index is called liquidity index
• The ratio between plasticity index and flow index (i.e. slope of flow curve in case of liquid limit), is called toughness index
• All the above.