Could you try to clarify what that whole sense is based on? (Even if the basis doesn’t bring you to complete certainty in your view.)

“what” = “what is it based on”*

Pretty simple. For choice to be meaningful, there has to be some degree of understanding of the consequences of one’s actions and some ability to plan ahead. And animals don’t outwardly show significant abilities of that kind.
Of course, it could be that some rat, deep deep down, without our knowing, is planning for the future and weighing theoretical options—what will happen if… and what will happen if not… and taking into account considerations like whether its rat friend will be deeply offended if it doesn’t greet her warmly, or not. But there’s no behavioral indication of that.