You went on a college trip with your friends and there you saw that some of your friends have started arguing on some issue. You wanted to be a mediator but one of them is doubting you for partiality. You will
1
Stop mediation and let them solve their dispute on their own.
2
Start taking his side to compensate for his doubt.
3
Call the police to interfere with the matter and leave.
4
Make him realize your unbiased approach.