Answer:
commensalism
Step-by-step explanation:
The kind of interaction between two organisms in which one is benefited while another one is neither benefited nor harmed is known as commensalism. Here, in this example remora fish is using sharks for transportation through oceans for free and conserving its own energy but shark is not getting any benefit from remora fish in turn.
Other options are incorrect because in mutualism both the organisms get benefited out of each other not just one. In parasitism and predation both, one of the organisms gets benefited while another one is harmed due their interaction with each other.