Question

which method of protection involves vertical sidewalls with horizontal struts?
trench boxes
sloping
benching
spoiling

Explanation:

Trench boxes are structures used in excavation work. They consist of vertical sidewalls that provide support to the sides of the trench. Horizontal struts are used within the trench box to further reinforce and stabilize the structure, preventing the sides from caving in. Sloping involves creating inclined sides of an excavation. Benching creates stepped - like horizontal platforms in the excavation sides. Spoiling refers to the mounding of excavated material.

Answer:

Trench boxes