Crystal structures with ions must have a. a 2+ charge b. a negative charge c. electrical neutrality d. a positive charge

Crystal structures with ions must have c. electrical neutrality.
There are positive cations and negative anions in crystal structures, there can be more cations or anions, but summ of positive and negative charges in crystal structures are equal.
For example BaCl₂, barium cation is 2+ and chlorine anions are 1- (2-).

Maybe you should get some from your teacher and learn more so you can get your grades up and maybe study a bit more

; lc