Which observation shows that centrioles are not essential for cell division?

1. The centrosome replicates itself before a cell divides, and its centrioles appear to help pull duplicated chromosomes apart. 2. That appearance alone does not prove the centrioles are required. 3. A structure is essential only if division fails without it. 4. Cells that have had the centrosome removed can still divide. 5. Plant cells, which lack centrosomes altogether, are capable of cell division. 6. Replication before division and the right-angle geometry are descriptions of the centrosome, not tests of necessity. 7. The telling observation is that plant cells divide without centrioles. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 4 "Cell Structure", section 4.3 Eukaryotic Cells_