While laying the railway tracks on wooden plank,a small gap is left between the successive lengths of rail because

The correct option is A It no gap is left, the expansion of rails will cause them to bend sideways
The rails of railway tracks are made up of steel.in summer,due to considerable rise in atmospheric temperature, the rails tend to increase in length,so they bend sideways if they are not allowed to increase in length.therefore while laying the railway tracks on wooden plank,a small gap is left between the successive lengths of rail.