The correct identification is:
B.) earthquakes: open large cracks in the earth crust; Tsunami: erosion of beaches.
To elaborate:
- Earthquakes can indeed lead to the formation of large cracks or faults in the Earth's crust due to the release of stress along tectonic boundaries.
- Tsunamis can cause significant erosion of beaches as they inundate coastal areas, eroding both the land and any structures present.
Option A is partially correct, but it mistakenly attributes the movement of blocks of land to tsunamis, when that effect is more closely associated with earthquakes. Options C and D contain inaccuracies regarding the associations of each natural disaster's impacts.