In an ideal Brayton cycle with regeneration, argon gas is compressed from 100 kPa and 25C to

Question:

In an ideal Brayton cycle with regeneration, argon gas is compressed from 100 kPa and 25°C to 400 kPa, and then heated to 1200°C before entering the turbine. The highest temperature that argon can be heated in the regenerator is
(a) 246°C
(b) 846°C
(c) 689°C
(d) 368°C
(e) 573°C