Certain vascular structures in the brain produce cerebrospinal fluid. Which of the following is “true” of these structures?

Certain vascular structures in the brain produce cerebrospinal fluid. Which of the following is “true” of these structures?

1. they project into the cerebral venous sinuses
2. they constitute what is called a choroid plexus
3. these structures are located in the subarachnoid space
4. they are called arachnoid villi
5. * they are found only in the lateral ventricles