Resistance of every set:
r1 = 2 + 2 + 2 = 6 ohm
r2 = 2 + 2 + 2 = 6 ohm
r3 = 2 + 2 + 2 = 6 ohm
r4 = 2 + 2 + 2 = 6 ohm
Now, when the these resistances are put in parallel
1 / r = 1 / r1 + 1 / r2 + 1 / r3 + 1 / r4
1 / r = 1 / 6 + 1 / 6 + 1 / 6 + 1 / 6
1 / r = 4 / 6
r = 6 / 4
r = 1.5 ohm