<u>Answer:</u> The correct answer is Radium (Ra).
<u>Explanation:</u>
Energy level having highest value of principle quantum number which is 'n' will have the highest energy electrons.
For the given options:
<u>Radium (Ra):</u> The number of electrons present in this element are 88 and electronic configuration of this element is ![[Rn]7s^2](https://tex.z-dn.net/?f=%5BRn%5D7s%5E2)
It has 2 electrons in 's' orbital having n = 7.
<u>Neon (Ne):</u> The number of electrons present in this element are 10 and electronic configuration of this element is ![[He]2s^22p^6](https://tex.z-dn.net/?f=%5BHe%5D2s%5E22p%5E6)
It has 2 electrons in 's' orbital having n = 2.
<u>Aluminium (Al):</u> The number of electrons present in this element are 13 and electronic configuration of this element is ![[Ne]3s^23p^1](https://tex.z-dn.net/?f=%5BNe%5D3s%5E23p%5E1)
It has 2 electrons in 's' orbital having n = 3.
<u>Lanthanum (La):</u> The number of electrons present in this element are 57 and electronic configuration of this element is ![[Xe]5d^16s^2](https://tex.z-dn.net/?f=%5BXe%5D5d%5E16s%5E2)
It has 2 electrons in 's' orbital having n = 6.
Hence, the correct answer is Radium (Ra).