Answer: C. At $t=3.0\ \text{s}$ the graph gives $\omega=+2\ \text{rad s}^{-1}$ so the wheel rotates anticlockwise. The segment has a negative slope, so $\alpha<0$ because $\omega$ and $\alpha$ have opposite signs, the angular speed is decreasing.

A: identifies the rotation direction correctly but assumes negative angular acceleration means increasing speed.
B: reverses the stated sign convention: positive angular velocity is anticlockwise.
D: reads the angular velocity as negative; at this time it is positive, while the graph’s slope is negative.
Remember: angular speed decreases when angular velocity and angular acceleration have opposite signs.