The ionization energy of N is more than that of oxygen because

Explanation

The correct answer is that the ionization energy of nitrogen is higher than that of oxygen because nitrogen has half-filled p-orbitals. Half-filled orbitals are particularly stable due to reduced electron repulsion and increased exchange energy, making it harder to remove an electron. Option A is correct as it highlights this stability.Option B is incorrect because, although atomic size can affect ionization energy, the primary reason here is the stability of the half-filled orbitals. Option C is incorrect because the number of electrons does not directly influence the ionization energy difference in this context. Option D is incorrect because electronegativity pertains to the ability to attract electrons, not to ionization energy, which involves removing an electron.