Answer to Question 1
D
The first sign of impending cochlear damage is high-pitched tinnitus (ringing in the ears).
As injury to cochlear hair cells proceeds, hearing in the high-frequency range begins to decline.
The first sign of vestibular damage is headache, which may last 1 to 2 days. Nausea, unsteadi-ness, dizziness, and vertigo then begin to appear.
Answer to Question 2
a