A function is where one the inputs have only one output. In this case all we have to do is look at the x value (x,y) and see when it goes 1,2,3,4 and that means there are no repeating x and in that case each input has only one output. If you look at the other ones they have a repeating x and that means the input has two outputs and therefore it isn't a function.
So there are 16 cokes in total... the probability of selecting a cherry coke is 9/16 the probability of selecting a coke zero is 4/16 for there to be no replacement I guess you could combine diet cokes with coke zero because they are both cokes.. I don't know EXACTLY how to get the probability without a replacement.. sorry