In which of the following pairs the ions are isoelectronic?

Options

A. `Na^(+),Mg^(2+)`
B. `Al^(3+).O^(-)`
C. `Na^(+),O^(2-)`
D. `Na^(3-),Cl^(-)`

Explanation

To determine which pairs of ions are isoelectronic, we need to identify the number of electrons in each ion and see if they are the same. Isoelectronic species are defined as ions or atoms that have the same number of electrons.

### Step-by-Step Solution:

1. **Identify the Ions and Their Ground State Electron Counts**:
- **Sodium (Na)**: 11 electrons
- **Magnesium (Mg)**: 12 electrons
- **Aluminum (Al)**: 13 electrons
...