The correct answer to this question is A, OTEC, which stands for ocean thermal energy conversion. OTEC is both a process and a technology. It is responsible for producing energy from differences in the ocean waters temperature waves. The temperate difference has to be at least 77 degrees Farenheit.
Seawater is used to produced desalinated water and it operates as the working fluid. OTEC research began in the United States in 1974. The establishment of the Natural Energy Laboratory of Hawaii Authority began this research. It is now one of the largest facilities for testing OTEC research in the world.