Which part of the ear is known as the visible portion and includes the ear canal?

The outer ear is the correct choice because it encompasses the visible structures of the ear, which include the pinna (the flap of cartilage and skin that is seen on the outside of the head) and the ear canal that leads to the eardrum. This section of the ear plays a crucial role in collecting sound waves from the environment and funneling them into the ear canal.

The middle ear, in contrast, is an internal part of the ear that contains the ossicles (small bones) and is involved in sound conduction but is not visible externally. The inner ear is responsible for hearing and balance and is located further within, containing structures such as the cochlea and vestibular system which are critical for auditory processing and spatial orientation. The tympanic membrane, also known as the eardrum, is a membrane that separates the outer ear from the middle ear and is crucial for sound transmission, but it does not comprise the visible portion of the ear, nor does it include the ear canal itself.