The thin membrane that divides the outer ear from the middle ear is known as the: eardrum pinna cochlea ossicle

The correct answer is A. Eardrum

Explanation

The auditory system is divided into three parts, the outer ear, the middle and the inner ear. The external ear is composed of three main parts, the ear that is the outer cavity through which the sounds enter, the ear canal, a cavity of about 2.5cm through which the sounds pass until they reach the tympanum, a membrane that separates the outer ear from the inner ear, where the small bones called hammer, anvil and stirrup are located. So, the correct answer is A. Eardrum.