Answer: High Frequency waves by method of compression bone conduction
Explanation: in this, vibration of the bones of the skull and sometimes, arguably soft tissues leads to the production of sounds. The outer and middle ear is bypassed in this method of sound production. Sound reaches the inner ear directly and its a process largely involved in designing hearing aids.
It was developed by a Swedish<em> </em>Botanist<u> </u><em><u>Linnaeus</u></em> in 17th century.
I believe the answer is c
