Four rods with different radii r and length l are connected to two reservoirs at different temperature. Which one of them will conduct most heat

The heat conduction per unit time is given by,
dq/dt = k(t₁ - t₂)A/l
=> dq/dt = k(t₁ - t₂)πr²/l
=> dq/dt ∝ r²/l
hence we can see that the heat conduction is directly proportional to the radius and inversely proportional to the length.
So heat conduction is maximum when r is maximum and l is minimum.
Hence the rod with maximum radius and minimum length will conduct maximum heat.