The correct answer is the spindle tubes.
The spindle tubes are cell structures that are formed from microtubules prior to cell division.
The microtubules of the spindle tubes attach to the chromosome pairs on the one side and to centrosomes on the other side. The centrosomes present two structures on opposite sides of the cells, that ''anchor'' the spindle tubes.
The separation of the chromosomes happens when the tubules start to contract towards the centrosomes, pulling the chromosome pairs apart.