Both systems prevent excessive rudder deflection at high speed.

By changing the ratio, even a full movement of the pedals will not give full deflection of the rudder. So the rudder movement is limited, but not the pedals. (i.e. not both, so I is wrong)

A variable stop system progressively limits deflection of the rudder as speed is increased, but by physically constraining it, NOT by changing the ratio. But within the range of motion that it has, the same relationship between pedal deflection and rudder deflection exists. (the ratio does not change, so II is wrong)