How fasciola hepatica show alternation of generations ?

Alternation of generations is a sexual life cycle transitioning between two multicellular reproductive generations, the haploid ( number of chromosomes) gametophyte generation, and the diploid ( number of chromosomes) sporophyte generation. Alteration of generations is the phrase to describe the life cycle of typical plants, like the land plants you are used to seeing, trees, bushes, also algae and such, and it is told from a genetic point of view.  It is the process of a mature plant with a normal count of chromosomes, producing spores, which have half the number of chromosomes (analogous to egg cells and sperm cells in mammals).  The spores later combine in plant sexual reproduction to produce viable plant seeds, and this process facilitates diversity and response to evolutionary pressures in plants.