virginia's therapist notes that virginia jumps from one topic to another and her replies are only tangentially related to the therapist's questions. this describes which symptom of schizophrenia?

This describes loosening of associations.
Another name for this symptom of schizophrenia is derailment. It refers to the fact that the person suffering from schizophrenia is likely to change subjects often, without actually thinking much about any of them. These subjects are usually either loosely related, or completely unrelated.