Final answer:
The part of an otoscope from the provided options is C. the speculum. The malleus, also known as the hammer, is instead one of the three ossicles of the middle ear and not a component of the otoscope.
Step-by-step explanation:
The part of an otoscope that is included in the provided options is C. the speculum. The otoscope is a tool used by medical professionals to examine the ear canal and tympanic membrane. A speculum is a piece that attaches to the otoscope and is inserted into the ear canal to allow for visual inspection. It is important to clarify that the malleus, or hammer, is one of the three bones of the middle ear known as the ossicles, which also include the incus (anvil) and stapes (stirrup), and are not parts of the otoscope.