Concept:
The spin-only magnetic moment is given by:
\[
\mu = \sqrt{n(n+2)} \text{ B.M.}
\]
where \(n\) is the number of unpaired electrons.
Greater the number of unpaired electrons, greater is the magnetic moment.
Step 1: Analyze the first set of complexes.
\[
[Fe(CN)_6]^{4-}
\]
Here:
\[
Fe^{2+} : 3d^6
\]
Since \(CN^-\) is a strong field ligand, pairing occurs:
\[
n = 0
\]
\[
[Fe(CN)_6]^{3-}
\]
\[
Fe^{3+} : 3d^5
\]
Low-spin configuration gives:
\[
n = 1
\]
\[
[Fe(H_2O)_6]^{3+}
\]
\(H_2O\) is a weak field ligand, so no pairing:
\[
n = 5
\]
Thus:
\[
0 < 1 < 5
\]
Hence the increasing order is correct.
Step 2: Apply the same logic to sets II and III.
For the remaining sets, the complexes are arranged according to increasing number of unpaired electrons, so their magnetic moments also increase correctly.
Therefore, all three arrangements are correct.
Hence:
\[
\boxed{(B)\ I,\ II,\ III}
\]