Concept:The structure labelled I is part of the machinery that moves chromosomes during cell division.
Explanation:The labelled part is a thread-like fibre running from the cell pole towards the chromosomes.
This fibre is known as a spindle fibre.
Spindle fibres attach to chromosomes and help separate them properly during division.
The centromere is the region where sister chromatids are joined, not this fibre.
The centriole is a small organelle found near the nucleus, while chiasmata are points of crossing over.
Therefore, the labelled part is not any of these other structures.
Answer:B. spindle fibre
