A horizontal rod rotates about a vertical axis through one end. A ring, which can slide along the rod witgour friction, is initially close to the axis and then slides to the other end of the rod. In this process, which of the following quantities will be conserved?
{L = angular momentum, `E_(T)` = total kinetic energy, `E_(R)` = rotational kientic energy.]
A. L only
B. L and `E_(T)` only
C. L and `E_(R)` only
D. `E_(T)` only
