The shielding of electrons gives rise to an effective nuclear charge, Z eff which explains why boron is larger than oxygen. Estimate the approximate Z eff felt by a valence electron of boron and oxygen, respectively? Please explain (I don't want just the answer).
A. +5 and +8
B. +3 and +6
C. +5 and +6
D. +3 and +8
E. +1 and +4