Which of the choices below is the best description of how parasitism differs from predation?

a.) in predation, one organism always benefits. in parasitism, either both organisms benefit an equal amount or both organisms are harmed an equal amount.
b.) in predation, one organism is always harmed, as it is always killed. in parasitism, one organism may be by the interaction while the other is unaffected.
c.) one organism is always killed in both parasitism and predation, but a predator always kills the other organism more quickly than a parasite.
d.) one organism is harmed in both parasitism and predation, but only parasitism involves an organism that coexists with another organism by living on or in it.

The correct answer is option D) One organism is harmed in both parasitism and predation, but out of these two only parasitism involves an organism that coexists with another organism by living on or in it.

In both the interactions i.e. parasitism and predation, one organism is harmed whereas another one is benefited. But, the basic difference in both the interactions is that in predation one organism literally kills another one for obtaining food.  While in parasitism, one organism which is being benefited out of another one, lives in close association with it rather than killing it. The organism  on/in which the parasitic organism lives is called as host. The parasite uses the host for its survival and also harms it without giving any benefit to it.