Which of the following is not one of the three categories of mechanical waves a.)radio wave
b.)surface wave
c.)transverse wave
d.)longitudinal wave

Rradio wave is not a category of mechanical wave.

Explanation:

Radio wave is a type of electromagnetic wave not a mechanical wave

so here is the information for current research:

-nrel's geothermal analysts, scientists, and engineers perform a full range of research from developing advanced methods of locating and accessing geothermal resources to exploring innovative technologies to extract and produce clean energy from the heat of the earth

and here is the information for the technology of geothermal energy:

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-resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma

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-a geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building

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