Step 1: Apply Angular Velocity Formula
The angular velocity is given by:
\[
\omega = q B / m
\]
Step 2: Compute Angular Velocity
\[
\omega = (8 \times 10^7) \times (4 \times 10^{-3})
\]
\[
\omega = 32 \times 10^4 { rad } s^{-1}
\]
Thus, the correct answer is \( 32 \times 10^4 \) rad \( s^{-1} \).