Which limit indicates the transition point where further drying of the soil may cause cracking?

The correct choice is the shrinkage limit, which is defined as the moisture content at which a soil transitions from a plastic state to a solid state with no further volume change upon drying. At this point, the soil can start to crack if drying continues. The shrinkage limit is crucial in understanding how soils behave as they lose moisture, and it indicates the maximum moisture level at which the soil can shrink without developing cracks.

Other limits such as the liquid limit and the plastic limit represent different states of soil behavior; the liquid limit pertains to the moisture content where the soil turns from a plastic state to a liquid state, while the plastic limit represents the moisture content under which the soil is still malleable but can no longer be molded without cracking. The plasticity index measures the range of moisture content between the liquid and plastic limits but does not explicitly indicate the point where additional drying leads to cracking. Hence, the focus on the shrinkage limit is critical when discussing the transition to cracking in soil due to further drying.