O is the center of the circle
AT is tangent to the circle at point T
$$\begin{aligned}
& | A T | = 3 \mathrm {~cm} \\
& \mathrm {~m} ( \widehat { \mathrm { OAT } } ) = 45 ^ { \circ }
\end{aligned}$$
According to the given information, what is the length of arc BT in cm?\\
A) $\frac { \pi } { 2 }$\\
B) $\frac { 2 \pi } { 3 }$\\
C) $\frac { 3 \pi } { 4 }$\\
D) $\frac { 4 \pi } { 5 }$\\
E) $\frac { 5 \pi } { 6 }$