A large cylindrical rod of length L is made by joining two identical rods of copper and steel of length `((L)/(2))` each. The rods are completely insulated from the surroundings. If the free end of copper rod is maintained at `100^(@)C` and that of steel at `0^(@)C` then the temperature of junction is (Thermal conductivity of copper is 9 times that of steel)

Options

A. `90^@ C`
B. `50^@ C`
C. `10^@ C`
D. `67^@ C`