A Wheel Rotates with a Constant Angular Acceleration Of $\pi$ Rad/s² $\pi$

A wheel rotates with a constant angular acceleration of $\pi$ rad/s². During a certain time interval its angular displacement is $\pi$ rad. At the end of the interval its angular velocity is 2 $\pi$ rad/s. Its angular velocity at the beginning of the interval is:

A) zero
B) 1 ras/s
C) $\pi$ ras/s
D) ras/s
E) 2 $\pi$ ras/s