Do animals know about choices? A mouse goes through a maze and gets to a T-junction. Does it "know" there is a choice to be made between left and right or does it just continue following it's nose? Perhaps using some heuristics?

An ape is given a choice of toys to play with. Does it know there is a choice and consider each in turn? Or just grab one on instinct?

A human gets to a T-junction in a maze. And you can garuntee that he or she will stop there for a while considering their options and imagining the best route forward.

So I wonder if "choice" is a thing that only humans (and maybe apes and crows) understand because they are the only ones who can make use of this by considering the future events?

Also, apart from the artificial example of a T-junction in a maze, what other examples of "choices" exist in the wild.
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.