Final answer:
The cross-reference term that is used to look elsewhere in the alphabetic index and is also optional is B) See.
Step-by-step explanation:
The cross-reference term that is used to look elsewhere in the alphabetic index and is also optional is B) See. When a student sees the term 'See' in the index, it means that the desired information is located under a related term or another heading. This is different from 'See also' (option B), which suggests additional related information.