Answer:
It will require a force of 1/5, answer A.
Explanation:
In the attached image we can see an example of an array of pulleys that will lift a 100 kg-f load.
If we analyze pulleys A,B, and C as in the image we can check a force in the cable of 20kg-f.
In the pulley D we have three forces of 20 kg-f each and those forces plus the forces in the pulley B, sum a total of 100 kg-f (60+40). This matches the mechanical advantage (100/5) = 20 kg-f
