Tough question, really. But at the end I think that it is D:
- A can't be, because the molecule of DNA in the chromatids is coiled, not linear
- B can be excluded, because the telomeres don't prevent loss of genes in cell divison. Their lengths at the ends of non-coding DNA restrict the divison. If they are too short, cell division stops.
- C is wrong, because the centromere contains DNA.