The IUPAC nomenclature of an element with electronic configuration $$[Rn] 5f^{14} 6d^1 7s^2$$ is

The electronic configuration is $$[Rn] 5f^{14} 6d^1 7s^2$$.

Radon (Rn) has atomic number $$Z = 86$$.

The configuration contributes $$5f^{14}$$ (14) + $$6d^1$$ (1) + $$7s^2$$ (2) = 17 electrons, giving $$Z = 86 + 17 = 103$$, which corresponds to the element Lawrencium (Lr).

For element 103, the IUPAC systematic name uses the roots for each digit:

- 1 → un

- 0 → nil

- 3 → tri

Adding the suffix "-ium": Unniltrium

Therefore, the correct answer is Option C: Unniltrium.