An Object Is Rotating with an Angular Acceleration Given By \alpha

Multiple Choice

An object is rotating with an angular acceleration given by $\alpha = c + d t ^ { 2 }$ , where $\surd$ is in radians/s², t is in seconds, c = -3.0 rad/s², and d = 0.40 rad/s⁴. At t = 2.0 s the angular acceleration of the object is

A) -2.2 rad/s².
B) -1.4 rad/s².
C) 3.8 rad/s².
D) 4.6 rad/s².