The difference in the second ionization energies of Li/Na, Be/Mg, B/AI and N/P are X1, X2, X3 and X4, respectively. The correct order of the difference in the second ionization energies is
1
X1 > X4 > X3 > X2
2
X1 > X2 > X3 > X4
3
X4 > X3 > 1 > X2
4
X1 > X3 > X4 > X2