3. A. A model car racer remotely controls a car. The car first moves forward 1 meter, then rotates counterclockwise by an angle $\alpha\left(0^{\circ}<\alpha<180^{\circ}\right)$, which is called one operation. If after five operations, the car returns to the starting point, then the value of angle $\alpha$ is ( ).
(A) $72^{\circ}$
(B) $144^{\circ}$
(C) $108^{\circ}$ or $144^{\circ}$
(D) $72^{\circ}$ or $144^{\circ}$
3. A. D.

If $0^{\circ}<\alpha<90^{\circ}$, then the trajectory of the race car forms a regular pentagon with an exterior angle of $\alpha$ and a side length of 1 meter.
Thus, $\alpha=360^{\circ} \div 5=72^{\circ}$.
If $90^{\circ}<\alpha<180^{\circ}$, then the trajectory of the race car forms a five-pointed star by connecting the endpoints of the diagonals of a regular pentagon with a diagonal length of 1 meter.
Thus, $\alpha=2 \times 72^{\circ}=144^{\circ}$.