The correct option is E Parasitism
Tapeworm resides in the human intestine where ample of pre-digested food is already present. For this reason, tapeworm lacks any gut as it does not need to digest the food rather have integument to allows absorption of nutrients directly from the host small intestine by diffusion. Human is harmed by the presence of tapeworm and develop several gut infections. Association of organisms where one of the partners is benefitted at the expense of other is called as parasitism. Thus, the correct answer is option E.