Because the predicate compliment is plural, I would lean toward "are" in this sentence.
1. Are either or both of the following, redox reactions?
2. Is either or both of the following, redox reactions?
#2 would normally be used (on the principle of applying the verb to the closest element of the subject in an A or B subject.) Do you agree?
I need native speakers' help.
So would I. Would anyone else take out the comma?