$B$. The drift velocity is inversely proportional to the area of cross-section of given conductor.
$C$. The drift velocity does not depend on the applied potential difference to the conductor.
$D$. The drift velocity of electron is inversely proportional to the length of the conductor.
$E$. The drift velocity increases with the increase in the temperature of conductor.
Choose the correct answer from the options given below:
$v _{ d }=\left(\frac{ e \tau}{ m }\right)\left(\frac{\Delta V }{\ell}\right)$
$\Delta V=$ Potential difference applied across the wire
As temperature increases, relaxation time decreases, hence $V _{ d }$ decreases.
As per formula, $V _{ d } \propto \frac{1}{\ell}$
$v _{ d }=\frac{ I }{\text { neA }}$, as it is not mentioned that current is at steady state neither it is mentioned that $n$ is constant for given conductor. So it can't be said that $v _{ d }$ is inversely proportional to $A$.
$I=n e A v_{d}=\frac{V}{R}=\frac{V}{\rho \ell} A$
$v _{ d }=\frac{ V }{\rho \ell \text { ne }} \quad\left( E =\frac{ V }{\ell}\right)$
$v _{ d }=\frac{ eE \tau}{ m }$
$\tau$ decrease with temperature increase.
First and fourth statements are correct.



