Find the correct statement about the eustachian tube

The correct option is Both (b) and (c).

Let us analyze the structure and function of the Eustachian tube step-by-step to understand why this option is correct:
1. Anatomy and Connection: The Eustachian tube (also known as the auditory tube) is a canal that connects the middle ear cavity to the nasopharynx (the upper part of the throat/pharynx behind the nasal cavity). Therefore, statement (c) "connects middle ear to pharynx" is anatomically correct.
2. Physiological Function: The primary role of the Eustachian tube is to ventilate the middle ear space, ensuring that its pressure remains equal to the ambient air pressure (outer atmospheric pressure). It normally remains closed but opens during activities like swallowing, yawning, or sneezing to let air pass between the pharynx and the middle ear. This equalizes the pressure on both sides of the tympanic membrane (eardrum), protecting it from damage and allowing it to vibrate properly for sound transmission. Thus, statement (b) "it equalises pressure between middle ear and outer atmosphere" is also correct.
3. Incorrect Statement: Statement (a) is incorrect because the Eustachian tube does not connect the internal ear to the external ear. The external ear is separated from the middle ear by the tympanic membrane, and the internal ear is a distinct fluid-filled structure (cochlea and vestibular system) located deeper within the temporal bone.

Since both statements (b) and (c) are scientifically accurate, the correct option is indeed Both (b) and (c).