A

20-year-old woman comes to the clinic after missing her last 2 periods. Her

cycles are usually regular, occurring at 28-30 day interval with moderate

bleeding and occasional abdominal pain. She also complains of progressively

diminishing peripheral vision. Her doctor determined the loss of vision in the

lateral halves of both retinas. Which of the following is likely to be affected,

causing bitemporal hemianopsia in the patient?

The test is

about: