Find the Radian Measure of the Central Angle of a Circle

Multiple Choice

Find the radian measure of the central angle of a circle of radius r that intercepts an arc of length s.

A) $\theta = \frac { 1 } { 7 }$ radians
B) $\theta = 6$ radians
C) $\theta = \frac { 1 } { 6 }$ radians
D) $\theta = 21$ radians
E) $\theta = 54$ radians