Consider a gas turbine that has a pressure ratio of 4.9 and operates on the Brayton cycle with regeneration between the temperature limits of 17°C and 960°C. If the specific heat ratio of the working fluid is 1.3, the highest thermal efficiency this gas turbine can have is
A. 33.9%
B. 2.6%
C. 66.1%
D. 97.4%