The correct option is B Commensalism
Commensalism is a kind of relationship where one organism is benefited while the other is unaffected. By attaching itself to a leopard shark, Remora is carried along on the shark's power. This allows Remora to travel to different areas without having to expend its own energy to swim. The shark is completely unaffected by the Remora's presence.
Thus, the correct answer is B.