The smallest bone in the human body is the stapes, which is located in the middle ear. It is about the size of a grain of rice and is shaped like a stirrup. The stapes is one of the three bones in the middle ear, which also includes the malleus and incus. These bones transmit sound waves from the eardrum to the inner ear. The stapes is the last bone in this chain, and it transmits sound waves to the oval window, which is a small opening in the inner ear. The oval window is connected to the cochlea, which is a fluid-filled structure that contains the auditory nerve. The auditory nerve sends signals to the brain, which interprets them as sound.
The other options are incorrect because they are not bones. Nails are made of keratin, which is the same material that makes up hair and skin. The fibula is a long bone in the lower leg. The bones of the nose are part of the facial skeleton.