The two ends of a rod of length $L$ and a uniform cross-sectional area $A$ are kept at two temperatures $T_{1}$ and $T_{2}$ $(T_{1} > T_{2})$. The rate of heat transfer,$\frac{dQ}{dt}$ through the rod in a steady state is given by:

• A
  $\frac{dQ}{dt} = \frac{k(T_{1} - T_{2})}{LA}$
• B
  $\frac{dQ}{dt} = kLA(T_{1} - T_{2})$
• C
  $\frac{dQ}{dt} = \frac{kA(T_{1} - T_{2})}{L}$
• D
  $\frac{dQ}{dt} = \frac{kL(T_{1} - T_{2})}{A}$