Which of the following statements is/are correct?
(i) The ratio of the speed of light to the speed of sound is called the Mach number.
(ii) Speed of sound increases with increase in temperature.
(iii) For hearing a distinct echo, the minimum distance of the obstacle from the source of sound should be 34.4 m.
(iv) Wavelength of sound audible to human lies between 17 mm to 17 m.

Options

A. (iii) only
B. (ii) and (iv) only
C. (i),(iii) and (iv) only
D. (i),(ii) , (iii) and (iv)

Answer

B