The correct option is
A Liver rot in sheep
Fasciola hepatica is known as the common liver fluke. This organism is also called as the sheep liver fluke because sheep acts as one of the host. This organism is a parasitic trematode. They belong to the class Trematoda and phylum Platyhelminthes. The fluke infects the livers of humans and other mammals. The disease or the infection which is caused is known as fasciolosis. They are commonly known to cause parasitic infections in sheep and cattles. Thus, the correct answer is option A.