NL- That is known only to God, but if he is it is the result of choices he freely made.
Of course it is a result of a choice he freely made. And that's the point. Left to our own devices we will always make the wrong choice. And one slip up is enough to be cast from the presence of God (as Adam found out).
The real question is whether we will make the right choices all the time. I believe Catholic doctrine would even say that Mary was incapable of doing that without God's grace.
Harley, we agree on this, I think. Our efforts to accept Grace and endeavor to not slip up is our cooperation with that Grace. And yes, Mary is full of Grace.