Which part of the ear is known as the deepest depression?

The concha is the correct answer because it refers to the deepest depression of the external ear, specifically the part that is situated just outside the ear canal. This structure plays a significant role in the ear's anatomy, as it helps collect and direct sound waves toward the ear canal. The concha's shape can enhance the ear's ability to hear by amplifying certain frequencies.

In contrast, other parts of the ear have different shapes and functions. The scapha is the shallow, curved area between the helix and the antihelix, serving as a structural component rather than a pronounced depression. The fossa typically refers to a small hollow or depression in the body and is not specifically associated with the ear's external structures in the same way. The helix is the outer rim of the ear and does not represent a depression but rather a prominent part of its anatomy.