Explanation

(d) Resistance of a conductor
$R = \frac{\rho l}{A}\ \ \ \ \ \ \ \ \ \ \ \ \ldots\ldots\ldots\ldots\ldots\ldots..(i)$
As $\rho$ depends on the material,
so R depends on the material.
According to the given formula in Eq.(i), it depends on length. Moreover resistance $\propto$temperature.
If $R_{0}$= resistance of conductor at $0{^\circ}\ C,$
$R_{t}$= resistance of conductor at $t{^\circ}C$,
and $a,\beta$ =temperature coefficient of resistance, then
$R_{t} = R_{0}\left( 1 + \alpha t + \beta t^{2} \right)$
The resistance of a straight conductor does not depend on shape of cross-section.