Explain how the radian measure of an angle is determined. Choose the correct answer below. O A. The radian measure of an angle 0 is the area of the sector bounded by the angle and an arc of a unit circle. O B. The radian measure of an angle 0 is double the length of an arc s on a unit circle associated with 0 O C. The radian measure of an angle 0 is the length of an arc s on a unit circle associated with 0. O D. The radian measure of an angle 0 is half the area of the sector bounded by the angle and an arc of a unit circle