Ionization energy increases in the order

$\mathrm{A})2{\mathrm{S}}^{2}2{\mathrm{P}}^6$ 

B)$2{\mathrm{S}}^{2}2{\mathrm{P}}^5$

C)$2{\mathrm{S}}^{2}2{\mathrm{P}}^5$

D)$2{\mathrm{S}}^{2}2{\mathrm{P}}^4$

Half filled (or) completely filled orbitals are more stable. In this orbitals we can remove electron very difficulty. To remove the electron more amount of energy is required. The increasing order of I.E 𝑂 < 𝑁 < 𝐹 < Ne