Neuropeptides are:

Correct Answer: A

Rationale: Neuropeptides are small protein-like molecules that act as neurotransmitters or neuromodulators, released by neurons to communicate with other cells. They are not glial cells, not produced by the choroid plexus (which makes CSF), nor nutrients.

Correct Answer: B

Rationale: The corpora quadrigemina (superior and inferior colliculi) are in the mesencephalon (midbrain), processing visual and auditory reflexes. Telencephalon is cerebrum, diencephalon includes thalamus, metencephalon is pons/cerebellum.

Correct Answer: D

Rationale: CSF is produced by the choroid plexuses but drains into venous sinuses (e.g., superior sagittal sinus), not the circle of Willis (an arterial structure). Other statements are accurate.

Correct Answer: B

Rationale: The telencephalon (cerebrum) is the most rostral brain region, farthest from the spinal cord. Myelencephalon (medulla) is closest, followed by metencephalon, mesencephalon, and diencephalon.

Correct Answer: C

Rationale: The pons (apneustic/pneumotaxic centers) and medulla oblongata (respiratory rhythm centers) regulate breathing. The hypothalamus influences autonomic functions but not directly respiration.