Final answer:
Replicated chromosomes remain closely attached at the centromere, a highly condensed region visible under a light microscope. Cohesin proteins also hold the sister chromatids together until they are separated during cell division.
"The correct option is approximately option A"
Step-by-step explanation:
After duplication, replicated chromosomes remain closely attached via the centromere. During DNA replication in the S phase of interphase, chromosomes become composed of two linked sister chromatids. These sister chromatids, which are identical, are bound together by cohesin proteins; however, the primary connection point is the centromere.
This region is highly condensed and appears as a constricted area, making it easily visible under a light microscope as the conjoined sister chromatids come together with a diameter of about 1 µm.
The kinetochore is another important structure involved during cell division, which becomes attached to the mitotic spindle allowing the chromosomes to be moved properly during mitosis. Meanwhile, during the prophase I of meiosis, it's the synaptonemal complex that plays a critical role in pairing and aligning the homologous chromosomes. Eventually, as the cell progresses through the later stages of cell division, cohesin proteins break down, allowing sister chromatids to separate and enable completion of cell division.