Of those four options, only 'each' takes a singular verb; the others require a plural verb.
'is' is a singular verb
Answer:
Each of my classes is interesting.
Explanation:
The word 'each' is used to refer to the individual things mentioned in a group of things. The things mentioned in the group or the list are similar to each other. In the above sentence, the classes which the reader is talking about have one thing in common that they all are interesting separately. Also, with 'each' the verb 'is' is used.
