The correct option is A Boron
The ionization energy increases for atoms or ions which already has a stable electronic configuration.
The electronic configuration of
B+→1s22s2
Be+→1s22s1
Mg+→1s22s22p63s1
Si+→1s22s22p63s23p1
So, in B+ the electron is to be removed from completely filled s-subshell, which is difficult. Thus, the second ionization energy of boron is maximum.