Without the ability to view Figure 9-1, I can't provide a specific answer. However, I can help clarify what each term refers to:
- Centromere: The region of a chromosome where two sister chromatids are joined and is essential for the proper segregation of chromosomes during cell division.
- Centriole: A structure that helps organize microtubules during cell division, part of the centrosome.
- Sister Chromatid: One of the two identical halves of a duplicated chromosome, which are joined together at the centromere.
- Spindle: Refers to the framework of microtubules that segregate chromosomes during cell division.
If you can provide additional context or details about the figure, I could help you determine which term is most appropriate.