Answer:
D. 3-
Step-by-step explanation:
Elements of group 15 are:
nitrogen with electronic configuration : 1s2 2s2 2p3
phosphorus with electronic configuration : [Ne] 3s2 3p3
arsenic with electronic configuration: [Ar] 3d10 4s2 4p3
antimony with electronic configuration: [Kr] 4d10 5s2 5p3
bismuth with electronic configuration: [Xe] 4f14 5d10 6s2 6p3
As we can note, all elements of group 15 have 5 electrons in their outermost energy levels.
To be stable, each of them needs to have 8 electrons in the outermost shell. This means that each needs to gain 3 more electrons.
Based on this, they will form negative ions having a charge of 3
Hope this helps :)