I think its 3. "ill be glad to come to ur house tmr" thats when theyre coming
Based on the given sentence above, the error that I can find is the incorrect use of the pronoun "their". Looking at the sentence, the subject is "One of your students", this means only one, and not all the students. Therefore, this should take a singular pronoun. So the correct sentence would be "One of your students left his or her book on the table." So the answer for this would be option A. Hope this helps.
Yea it's also a song so you can remember it, look it up on YouTube and you will remember it for your test :)