Park Patrol

The man and woman with the blue folders are members of Belgrade's street/park patrol, and cite persons for various infractions.  This man didn't have an issue, since his 'dangerous breed' dog is muzzled. He was asking exactly which breeds were considered dangerous.  He received, from what I was able to hear as I putzed around taking this photo, a very unclear answer.

Which breeds, in your option, could possibly be dangerous and should  be muzzled?