Two rods of same length and cross section are joined along the length. Thermal conductivities of first and second rod are `K_(1)` and `K_(2)`. The temperature of the free ends of the first and seconds rods are maintained at `theta_(1)` and `theta_(2)` respectively. The temperature of the common junction is
A. `(theta_(1)+theta_(2))/(2)`
B. `(K_(2)K_(2))/(K_(1)+K_(2))(theta_(1)+theta_(2))`
C. `(K_(1)theta_(1)+K_(2)theta_(2))/(K_(1)+K_(2))`
D. `(K_(2)theta_(1)+K_(1)theta_(2))/(K_(1)+K_(2))`
