Do you try to pause before reacting?

I used to automatically explain myself when I said no to anyone. Now, unless I feel an explanation is absolutely essential, I don't elaborate. "No" is a complete sentence! While I know it depends on the situation, do you usually say no and leave it at that?

I visited a few zoos when I was a child and left in tears because I felt sad that the animals were caged and couldn't roam free. While zoos may purport to treat the animals well, they still need/deserve to be in their natural habitat, do you agree (this is excluding the animals born in captivity and not knowing how to survive in nature)?

Do you walk away in these situations?