Step 1: Match each device to the haulage system it belongs to.
A back stay is the safety device fitted to direct rope haulage trains, it digs into the ground behind an ascending train if the rope breaks, so it belongs to a different haulage system than the one asked about here. Small man clips and cam clips are simply the fittings used to attach tubs onto the moving rope, they are operational hardware, not dedicated anti runaway safety devices.
Step 2: Think through what could go wrong specifically on an endless rope haulage incline.
In an endless rope system running on an inclined section, if the rope were to break, tubs already moving upward could start rolling backwards under gravity and gather dangerous speed before anyone could react, so a passive device is needed that automatically stops a runaway tub without needing power or human intervention.
Step 3: Describe how the monkey catch achieves this automatically.
A monkey catch is a short, hinged, weighted section of rail that normally sits in a raised position. A tub moving correctly, in the intended direction, simply pushes the catch down and rolls over it. But a tub running backwards out of control meets the catch still raised, its axle strikes the catch, and the tub is derailed and stopped safely before it can gather dangerous speed. This makes it the safety device specifically associated with endless rope haulage.
\[ \boxed{\text{Monkey catch}} \]