To Increase the Current Density in a Wire of Length $\ell$

To increase the current density in a wire of length $\ell$ and diameter D,you can

A) decrease the potential difference between the two ends of the wire.
B) increase the potential difference between the two ends of the wire.
C) decrease the magnitude of the electric field in the wire.
D) heat the wire to a higher temperature.
E) combine both (b) and (d) .