b
(b) If all are in series then ${R_{eq}} = 12\,\Omega $
If all are in parallel then ${R_{eq}} = \frac{4}{3}\Omega = 1.33\,\Omega $
If two are in series then parallel with third, ${R_{eq}} = \frac{8}{3} = 2.6\,\Omega $
If two are in parallel then series with third, ${R_{eq}} = 6\,\Omega $