Answer:

b) 18m

Step-by-step explanation:

as it is asking minimum length

it must be 17 as if the water level below ground is now 15 m after rain.

and the wall is 1.2m above the ground

and the pully is 0.8m above wall

then add them all

15 + 1.2+ 0.8 = 17m

17m is the distance between pulley and water

but there should be some length for him as well through which he could pull

so answer is 18m

Answer:

hope it is helpful to you