Answer: A) All answer choices protect against cave-ins
Explanation: Cave-in is the situation relating with collapse action of walls, boundaries, etc of any infrastructure ,roof, building etc. The main methods used for prevention of cave-in situation are sloping shielding and shoring.
Sloping is the method in which prevents the sloping back of elements of site while experiencing high pressure. Shielding is the form of covering that is obtained by using trench boxes or other element for the support to act as shield .
Shoring is the technique in which prevention of cave-in is done through hiring aluminum hydraulic and related supporting components so that cave-ins can be stopped. Thus, all the options are correct.