Tympanic membrane separates:
Go with B — External and middle ear. Within Sensory System Ear Physiology, that statement lines up with the standard definition and the usual exam wording you’ll see. In plain terms, External and middle ear is the option that correctly names the structure, process, or principle asked for in Sensory System Ear Physiology. Holding that picture in mind makes External and middle ear feel natural rather than something you only memorise. Link the term to a real body example (organ, tissue, or ion flow) so the idea stays concrete under exam pressure. A short mental diagram helps — start from stimulus or structure, follow the pathway, and stop at the functional result described by External and middle ear.
Ref: Animal physiology is Unit 7 of the CSIR NET Life Science Syllabus, covering core body systems. It accounts for roughly 10% of the total marks in Sections B and C.