Step 1: Equate the potential energy to the heat required for melting.
Assuming all the gravitational potential energy is converted into heat,
\[
mgh=mL_f,
\]
where
\[
L_f=3.36\times10^5\,\mathrm{J\,kg^{-1}}.
\]
Step 2: Calculate the height.
\[
h=\frac{L_f}{g}
=\frac{3.36\times10^5}{9.8}
\approx3.43\times10^4\,\mathrm{m}.
\]
Thus,
\[
h\approx34.3\,\mathrm{km}.
\]
Hence,
\[
\boxed{34.3\,\mathrm{km}}
\]
Therefore,
\[
\boxed{(D)}
\]
is the correct answer.