choice

I came across the following claim:
Given a choice, it either has a reason that caused it, or it doesn’t.
If it has… then it is deterministic. And if it doesn’t, then it is random (and I’m not really sure that the concept of random exists)
How can this be reconciled? In my opinion, there are constraints on a person, judgment, will and things that influence the thinking process until the choice. But the choice is up to him. But I don’t know how to explain it.