Concept:A first class lever has the fulcrum placed between the effort and the load.
Explanation:In a crowbar, the fulcrum lies at a fixed point, the load is at one end, and the effort is applied at the other end.
So a crowbar is a first class lever.
Common examples of first class levers are a see-saw, scissors, pliers, and a crowbar.
A bottle opener and a wheelbarrow are second class levers because the load is between the fulcrum and the effort.
A fishing rod is a third class lever because the effort is applied between the load and the fulcrum.
Hence, among the given options, only the crowbar matches the condition of a first class lever.
Answer:B. crow bar.