Two identical rods A and B are of equal lengths and at the same temperature. The rod A is placed at smooth surface but B is placed at rough surface. If the temp of both are raised by the same amount,then
(a) final length of A > final length of B
(b) final lengths of both are same
(c) final length of A
(d)none

option no 2 turns out to be the correct option . 
as the only diff between them is the smooth and the rough surface , as they donot move , so, frictional force will not come into play . 
so, as the temp. given to both of them will be same , then their length will be equal and if they expand then both will expand equally ..