Answer
c) is correct.
Work Step by Step
The second hand moves in a clockwise direction, so its angular velocity $\omega\lt0$
As the second hand slows down and comes to a halt, we have initial velocity $\omega_0\lt0$, final velocity $\omega=0$ and duration $t$. We can see that $$\alpha=\frac{\omega-\omega_0}{t}\gt0$$
So c) is correct.
