Type the verb that best completes the sentence.
either the teacher or the students (clean, cleans) the boards each day.

Clean because if you add cleans to the sentence and read it out loud it won't make sense . remember cleans is plural more than one . and clean is not . every time you see a s at the end it's plural . by the way boards has to do with it too . make sure to read this out loud . cleans the boards each day . it makes more sense when you read and write clean the boards each day 

Ibelieve it is entry b.