Certain animals communicate using frequencies outside the range detected by the human ear. Read the information given below and answer the questions that follow.
(i) The rumbling calls of an elephant have a typical frequency of 15 Hz. To which category of sound does this belong?
(ii) Bats emit clicking sounds of about 50 kHz while hunting. Identify the category of this sound.
(iii) Explain, giving any two scientific reasons each, why low-frequency sound is suitable for long-distance communication by elephants whereas very high-frequency sound is advantageous for bats in locating insects at night.