Given:
- protons \(=11\), so atomic number \(Z=11\), element is sodium
- neutrons \(=12\), so mass number:
\[
A=11+12=23
\]
Electrons \(=10\), but neutral sodium has \(11\) electrons. So one electron is lost:
\[
Na^+
\]
Thus the species is:
\[
\boxed{{}^{23}_{11}Na^+}
\]
Hence,
\[
\boxed{(B)}
\]