R is proportional to l
if u take 5ohm/p, length will be 0.6m for 3ohms
like if u take 10ohm/m.....length for 3 ohms would be 3/10...0.3 m
and if u take 20ohm/m....length for 3ohms would be 3/20.. 0.15m....I think would be suitable.
For least resistance in the resistor in itself....a smaller length would be preferred.
If anyone has another answer and a reason to justify it....go ahead...m not a master in physics
.....but from whatever knowledge i have...I would chose this