Auditory information from external sources is first processed by the __________ and lastly by the __________.

A) eardrum; auditory nerve
B) hammer; anvil
C) auditory nerve; hair cells
D) eardrum ;auditory cortex

Auditory information from external sources is first processed in the eardrum, then by the hammer and anvil in the middle ear, the cochlea in the inner ear, the auditory nerve, and finally by the auditory cortex in the brain. The eardrum is the first point of contact for incoming sound waves, and the auditory cortex is the final destination where sound is processed into meaningful information. Therefore, the correct sequence of auditory processing is eardrum, auditory nerve, and auditory cortex. Choice D correctly identifies the eardrum as the first point of processing and the auditory cortex as the last.