Assertion (A): A jet aircraft moving at mach number equal to 1 travels faster at an altitude of 15 km than while moving at mach number equal to 1 near the sea level.
Reason (R): The velocity of sound depends on the temperature of the surrounding medium.

A. Both (A) and (R) are true and (R) is the correct explanation of (A)

B. Both (A) and (R) are true, but (R) is not the correct explanation of (A)

C. (A) is true, but (R) is false

D. (A) is false, but (R) is true

Answer: Option D