What is the value of Mach number?

Question

The velocity of a gas flowing through a duct is 300 m/s, its temperature is 127⁰C, Gas constant R = 0.25 KJ/kg K, the ratio of specific heat is C_p/C_v = g = 1.6. What is the value of Mach number? 

(a) 0.70                        (b) 0.72           

(c) 0.75                        (d) 0.77