Which discontinuity might be a result of cooling in a casting?

Shrinkage is a type of discontinuity that can occur during the cooling process in casting. As molten material cools and solidifies, it tends to contract. This shrinkage can lead to voids or gaps within the material, which are categorized as shrinkage discontinuities. These discontinuities can manifest as internal or external defects, affecting the structural integrity and overall quality of the casting.

In contrast, blisters, surface finish discrepancies, and the assertion that no discontinuities would be found during cooling relate to different phenomena or are less directly associated with the cooling process. Blisters typically arise from gas entrapment rather than cooling shrinkage, while surface finish discrepancies involve minor imperfections related to the mold or the casting process itself. The option suggesting that no discontinuities would exist contradicts the reality of casting processes, where various discontinuities can inevitably arise due to the nature of material solidification.