Question

which method of protection involves vertical sidewalls with horizontal struts?
trench boxes
shoring
benching
spotting

Explanation:

Among the options, "Benching" involves creating horizontal levels (benches) with vertical sidewalls and horizontal struts for support in excavation protection. Trench boxes are more about using pre - fabricated boxes, shoring is a general term for support, and spoiling is about removing excavated material.

Answer:

Benching