The correct answer is A. 30.
The velocity ratio of a machine is the ratio of the distance moved by the effort to the distance moved by the load. In this case, the effort moves 1 meter for every 30 meters moved by the load. This means that the velocity ratio is 30.
The efficiency of a machine is the ratio of the work done by the machine to the work done on the machine. In this case, the machine does 6000 J of work on the load, and the effort does 200 J of work. This means that the efficiency is 60%.
The effort is the force that is applied to the machine to move the load. In this case, the effort is 200 N.
The load is the weight that is being lifted by the machine. In this case, the load is 6 kN.
To calculate the velocity ratio, we can use the following formula:
VR = $\frac{d_e}{d_l}$
where:
VR = velocity ratio
$d_e$ = distance moved by the effort
$d_l$ = distance moved by the load
In this case, we have:
VR = $\frac{1}{30}$
= 30
Therefore, the velocity ratio of the machine is 30.