Atomic structure — practice question

What is the electronic configuration of a lone $\text{Ni}^{2+}$ ion?

• A$1s^2 2s^2 2p^6 3s^2 3p^6 3d^6 4s^2$
• B$1s^2 2s^2 2p^6 3s^2 3p^6 3d^7 4s^1$
• C$1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^2$
• D$1s^2 2s^2 2p^6 3s^2 3p^6 3d^8$