Three identical conducting rods are connected as shown in the figure Choose the correct options.

$$\begin{gathered} {\mathrm{Q}}_{\mathrm{AC}}+{\mathrm{Q}}_{\mathrm{BC}}={\mathrm{Q}}_{\mathrm{CD}} \\ \mathrm{As} \mathrm{they} \mathrm{are} \mathrm{identical} \end{gathered}$$

${\mathrm{T}}_{\mathrm{A}}-{\mathrm{T}}_{\mathrm{C}}+{\mathrm{T}}_{\mathrm{B}}-{\mathrm{T}}_{\mathrm{C}}={\mathrm{T}}_{\mathrm{C}}-{\mathrm{T}}_{\mathrm{D}}$

$40-{\mathrm{T}}_{\mathrm{C}}+30-{\mathrm{T}}_{\mathrm{C}}={\mathrm{T}}_{\mathrm{C}}-20$

$$\begin{gathered} 3{\mathrm{T}}_{\mathrm{C}}=90 \\ {\mathrm{T}}_{\mathrm{C}}=30{}^0\mathrm{C} \end{gathered}$$

Heat flows through CD as it has temperature difference.