Answer
The work done by the tension is zero.
Work Step by Step
At every point around the circle, the angle $\theta$ between the displacement vector and the direction of the tension is $90^{\circ}$. Therefore;
$W = \int ~T~ds~cos(\theta)$
$W = \int ~T~ds~cos(90^{\circ})$
$W = \int ~T~ds~(0)$
$W = 0$
The work done by the tension is zero.
