Match the following species with their respective number of electrons:
| Species | Number of electrons |
| :--- | :--- |
| $(a)$ $O^{2-}$ | $(i)$ $18$ |
| $(b)$ $Li^{2+}$ | (ii) $2$ |
| $(c)$ $He$ | (iii) $10$ |
| $(d)$ $Ca^{2+}$ | (iv) $1$ |

• A
  $a-iii, b-iv, c-ii, d-i$
• B
  $a-ii, b-iii, c-i, d-iv$
• C
  $a-iii, b-iv, c-i, d-ii$
• D
  $a-iv, b-iii, c-ii, d-i$