Which type of energy source is harnessed in this scenario?

Geothermal energy is derived from the heat stored within the Earth, typically harnessed through steam or hot water from underground reservoirs. This energy source is unrelated to ocean currents and does not apply to the scenario, which focuses on the kinetic energy of water movement rather than thermal energy from the Earth's interior.

Wind energy is generated by capturing the kinetic energy of moving air using turbines. While both wind and tidal energies involve the conversion of kinetic energy, the question specifically refers to water currents rather than air currents, making wind energy an incorrect choice in this context.

Biomass energy originates from organic materials, such as plant and animal waste, which are converted into usable energy through processes like combustion or fermentation. This energy source bears no relation to the movement of ocean water, which is the focus of the question, thus ruling it out as a viable option.