Tracts of white matter which connect the right and left hemispheres are composed of:

Correct Answer: C

Rationale: Commissural fibers (e.g., corpus callosum) connect the right and left cerebral hemispheres. Decussation fibers cross midline, association fibers connect within one hemisphere, and projection fibers link cortex to lower structures.

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.