The correct choice is C .
Technically, choice-A is the process involved. But it's already been done,
and widely published, and the spectrum of every element is easily available.
For you to take the time and go to the trouble of constructing the spectra
would be like inventing wheels if you want to ride a bicycle.
Answer:

Explanation:
The capacitance of the parallel-plate capacitor is given by

where
ϵ0 = 8.85x10-12 C2/N.m2 is the vacuum permittivity
k = 3.00 is the dielectric constant
is the area of the plates
d = 9.00 mm = 0.009 m is the separation between the plates
Substituting,

Now we can calculate the energy of the capacitor, given by:

where
C is the capacitance
V = 15.0 V is the potential difference
Substituting,
