What Is the Gear Ratio (Rear to Front) of a Bicycle

What is the gear ratio (rear to front) of a bicycle that has 46 teeth on the rear sprocket and 50 teeth on the front sprocket?

A) $\frac { 23 } { 25 }$
B) $\frac { 1 } { 46 }$
C) $\frac { 1 } { 50 }$
D) $\frac { 48 } { 25 }$
E) $\frac { 25 } { 23 }$