Answer: Reproductive organs,
Flukes generally have high reproductive rate, Most are hermaphrodite. Therefore the cavity is occupied by the male and female reproductive organs.
The male reproductive part consists of two testis, sperm storage sacks.And mating organs can be cirrus or penis depending if they can be drawn in the body or not.
Only one ovary exists, Vitelline gland is present to produces yolk cells, and shell gland,;Mehlis's gland produce shells.
They belong to phylum platyhelminthes, and they are endoparasites. They attach to their hosts through paired hooks on their heads to absorbs metabolites.
Explanation: