1. Find the atomic number from the electronic configuration

Given configuration: $[Rn] \, 5f^{14} 6d^1 7s^2$

Radon has atomic number: $Z = 86$

Electrons beyond radon:

• $5f^{14}$ contributes $14$
• $6d^1$ contributes $1$
• $7s^2$ contributes $2$

So total atomic number is: $Z = 86 + 14 + 1 + 2 = 103$

2. Write the temporary IUPAC systematic name for $Z=103$

The old systematic digit roots are:

• $1 \to$ un
• $0 \to$ nil
• $3 \to$ tri

For $103$, combine the roots in order: $1\;0\;3 \Rightarrow \text{un-nil-tri-ium}$

So the name is: $\boxed{\text{Unniltrium}}$

3. Match with the options

• A: Unnilbium $\to 102$ (wrong)
• B: Unnilunium $\to 101$ (wrong)
• C: Unnilquadium $\to 104$ (wrong)
• D: Unniltrium $\to 103$ (correct)

Therefore, the correct option is: $\boxed{D}$