Do animals know about choices?
What (with proper null and experimental method) do you mean by "heuristic"?

What (with proper null and experimental method) do you mean by "instinct"?

What (with proper null and experimental method) do mean by "considering"?

This is a situation where psychological language meets the imperfections of experimental neuroscience. Typical neuroscience tasks are simple because they attempt to isolate some particular behavior in the most parsimonious way possible. Generalization to behavior in the natural state is far removed from this. e.g. consider the humble mouse. It takes 100's-1000's of trials to learn a 2AFC task with visual feedback. It takes ~6 trials (even in absence of cortex and hippocampus via Markus Meister) to learn a complex maze given the right reward condition. Context is everything and ethological context is missing from most modern behavioral assays. A mouse will escape from a looming stimulus with 0 training.

So, although I'm not a mouse myself (but I am an ape), I would say: the mouse "knows" just as well as you do.