I’m pretty good with functions, all the numbers in the domain can only have one range ☝ so if for example, 3 had a arrow going to 5 and 7. That wouldn’t be a function, because 1 function has 2 domains, and since you have no range its not a clarified answer meaning that there’s following domain to go with the range so I wouldnt really say it’s a function because the domains have not range to go to, hope this helped!! :D