Parasitism is the mode of association in which one organism is benefited and another one is harmed. So one organism is benefited at the cost of another.
Symbiosis means when 2 organisms mutually benefit each other and are interdependent on each other.
In predation, a predator preys on another organism.
in commensalism, one organism is benefited and the other one is unaffected.
So, option C " Commensalism" is the correct option.