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. ?
Radius r
Arc Length s
6 inches
?20 inches
?
?

A) ? = ?120 radians
B) ? = $\frac { 3 } { 10 }$ radians
C) ? = $\frac { 3 } { 13 }$ radians
D) ? = $\frac { 10 } { 3 }$ radians
E) ? = 26 radians