b
According to Ohm's law $R=\frac{V}{I}$
Where $R=$ resistance $V=$ Voltage $I=$ Current
Also $R$ is directly proportional to temperature $T$ and inversely proportional to the slope.
$\therefore$ from the above example
$R_{1} \propto T_{1}$ and $R_{2} \propto T_{2}$
but from given figure $R_{1} < R_{2}$
$\therefore T_{1} < T_{2}$