Answer:
Umberto will be liable only if he acted negligently and performed a bad excavation or did not take the proper measures to avoid the land to collapse. This is represented in option "d" and that will be the correct answer.
Explanation:
The remaining options a, b,c can be used if we know the land conditions and Umberto expertise doing excavations. The only thing we know is that the surface of the land collapse during the excavations.
