A. Step wells.
D. Cotton mills.
The worm shown in the picture above represents Guinea worm.
Dracunculiasis or guinea worm disease is caused by the nematodeDracunculus medinensis, or Guinea worm.
Infection occurs after swallowing water containing the infected intermediate host, the crustacean Cyclops (known as copepods or water fleas).
The habit of washing and bathing in surface water and using step-wells is important for infestation.