The drift velocity of electrons in a copper wire of length 2 m under the application of a potential difference of 200 V is $0.5 ms^{-1}$. The mobility of electrons in $m^2 V^{-1} s^{-1}$ is:

$2.5 \times 10^{-3}$ $5.0 \times 10^{-3}$ $2.5 \times 10^{-2}$ $5.0 \times 10^{-2}$

$5.0 \times 10^{-3}$

The correct answer is Option (2) → $5.0 \times 10^{-3}$