The correct answer is C. Helium.
The ionization potential is the energy required to remove an electron from an atom in its ground state. The higher the ionization potential, the more difficult it is to remove an electron from the atom.
Helium has the highest ionization potential of all the elements in the periodic table. This is because helium has a very stable electron configuration, with two electrons in its valence shell. The two electrons in helium’s valence shell are paired, which means that they have opposite spins. This makes it very difficult to remove one of the electrons from the atom, because doing so would require breaking the pair and creating two unpaired electrons.
Oxygen, carbon, and boron all have lower ionization
potentials than helium. This is because they have less stable electron configurations than helium. Oxygen has six electrons in its valence shell, which is two more than helium. Carbon has four electrons in its valence shell, which is one more than helium. Boron has three electrons in its valence shell, which is the same as helium.The less stable the electron configuration of an atom, the easier it is to remove an electron from the atom. This is because the electrons in a less stable electron configuration are more loosely bound to the atom.
Therefore, the element with the highest ionization potential is helium.