12 identical rods made of the same material are arranged in the form of a cube. The temperature of ‘p’ and ‘r’ are maintained at 90 °C and 30 °C respectively. The temperature of ‘v’ in steady-state is

(a) 60 °C
(b) 65 °C
(c) 50 °C
(d) 20 °C

Answer: (b) 65 °C