Student or Learner
What's the right answer between the two options?
That's my parents'car.
That's my parent's car.
I'm wondering if both of them are correct as the first is referring to mother and father and the second one only to one of them.
Am I right?
Belongs to both parents: That's my parents' car.
Belongs to one parent: That's my mother's car. That's my father's car. I can't think of a natural situation when you'd say "my parent's car" to mean that is belongs to one of your parents, but not the other.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.