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. [IAS Prelim]

• A. Both A are R are true and R is the correct explanation of A
• B. Both A and R are true but R is not a correct explanation of A
• C. A is true but R is false
• D. A is false but R is true