Differential settlement occurs when:

Differential settlement occurs specifically when one part of a structure settles more than another part, leading to the misalignment of walls, floors, and other structural components. This phenomenon can cause serious structural issues, such as cracks in walls, uneven floors, and compromised integrity of the building. It is often a result of uneven soil conditions beneath the foundation or the presence of moisture that affects soil stability differentially across the foundation.

Uniform settlement, as mentioned in one of the incorrect choices, would not lead to such issues because the building would sink evenly, reducing the likelihood of structural damage. A completely stable foundation, or only the roof experiencing settlement, does not capture the essence of differential settlement, which specifically involves varying degrees of settling between parts of the structure.