下拉列表保持从列表中选择最后一项

I have an issue with an assignment I'm working on at the moment. I have a drop down list where I can select a user to send them a message on my website. The problem is that every time I try to select something it will keep selecting the last item from the list instead. The code below is the one I declared at the top of my PHP file upon querying from the database table:I have an issue with an assignment I'm working