Periodic Table And Periodicity

If four different elements $\mathrm{A}, \mathrm{B}, \mathrm{C}$ and D having outer electronic configuration as,

\(\mathrm{A}=3 \mathrm{~s}^2 3 \mathrm{p}^4, \mathrm{~B}=3 \mathrm{~s}^2 3 \mathrm{p}^5, \mathrm{C}=4 \mathrm{~s}^2 4 \mathrm{p}^4, \mathrm{D}=4 \mathrm{~s}^2 4 \mathrm{p}^5\)

identify the element with lowest ionization enthalpy $\left(\Delta_1 \mathrm{H}_1\right)$