Which path would require the most external work to move a negative point charge

How is work related to potential difference? (Volts)

To the first one, the most external work does not at all depend on the path taken. It depends solely on the change in distance from its start point and the end point. If you post the actual picture I can tell you which path it is.

To the second one, Work = (charge) * (change in Voltage) = q * (delta V)

thx bro