Two reversible engine operate between thermal reservoirs at 1200 K, T2 K and 300 K such that 1st, engine receives heat from 1200 K reservoir and rejects heat to thermal reservoir at T2 K, while the 2nd engine receives heat from thermal reservoir at $T_{2}$ K and rejects heat to the thermal reservoir at 300 K. The efficiency of both the engines is equal What is the value of temperature $T_{2}$?
a. 400 K b. 500 K
c. 600 K d. 700 K