The question is asking for the term used to refer to a single part of a list or series. 'Item' (C) is the correct term for an individual piece in a list or series. 'Element' (A) and 'Component' (B) can also refer to parts of a whole but are more commonly used in the context of a system or a complex structure. 'Aspect' (D) refers to a part of something considered as a whole, often in a more abstract sense. Therefore, the correct answer is C.