Concept:
To find \(\sqrt{1+\sqrt{i}}\), first determine the values of \(\sqrt{i}\). Then compute the square roots of the resulting complex numbers and compare them with the given options.
Step 1: Find \(\sqrt{i}\).
Since
\[
i=\cos\frac{\pi}{2}+i\sin\frac{\pi}{2},
\]
its square roots are
\[
\pm\left(\cos\frac{\pi}{4}+i\sin\frac{\pi}{4}\right)
=
\pm\frac{1+i}{\sqrt2}.
\]
Taking the principal value,
\[
\sqrt{i}=\frac{1+i}{\sqrt2}.
\]
Hence,
\[
1+\sqrt{i}
=
1+\frac{1+i}{\sqrt2}
=
\frac{\sqrt2+1+i}{\sqrt2}.
\]
Step 2: Verify option (A).
Let
\[
z=\frac{\sqrt2+1+i}{\sqrt2}.
\]
Then
\[
z^2
=
\frac{(\sqrt2+1+i)^2}{2}
=
\frac{2+2\sqrt2+2(\sqrt2+1)i}{2}
=
1+\frac{1+i}{\sqrt2}.
\]
Thus,
\[
z^2=1+\sqrt{i}.
\]
Hence option (A) is a valid value.
Step 3: Verify options (C) and (D).
Option (C) is
\[
-\frac{1+\sqrt2+i}{\sqrt2},
\]
which is the negative of option (A). Therefore its square is also
\[
1+\sqrt{i}.
\]
Hence option (C) is also a valid value.
Similarly,
\[
-\frac{\sqrt2+1+i}{\sqrt2}
\]
corresponds to option (D), which is again a square root of the same number.
Step 4: Check option (B).
Let
\[
z=\frac{\sqrt2+1-i}{\sqrt2}.
\]
Then
\[
z^2
=
1+\frac{1-i}{\sqrt2}.
\]
This is not equal to
\[
1+\frac{1+i}{\sqrt2}
=
1+\sqrt{i}.
\]
Therefore option (B) cannot be a value of
\[
\sqrt{1+\sqrt{i}}.
\]
\[
\boxed{\dfrac{\sqrt2+1-i}{\sqrt2}}
\]