Find, if possible, a choice function for each of the following collections without using the axiom of choice.

(a) The collectionAof nonempty subsets of Z+

(b) The collectionBof nonempty subsets of Z

There are a (c) and (d) as well, but I am hoping that help with these first two will mean I can do the last two.

I do not know how to do this. If someone could explain the process and also give a little more in depth explanation of a choice function, it would really help me.

Thanks!