The correct answer is: C. Centromere.
The centromere is the region of a chromosome where the two sister chromatids are held together. It is also the site of attachment of the chromosome to the spindle fibers during mitosis and meiosis.
A chromomere is a bead-like structure that is visible on chromosomes during certain stages of cell division. Chromomeres are made up of DNA and protein, and they are thought to play a role in the organization of the chromosome.
A centrosome is a small organelle that is found in animal cells. It is responsible for organizing the microtubules that form the spindle during mitosis and meiosis.
A blastomere is a cell that is produced during the early stages of embryonic development. Blastomeres are derived from the zygote, and they divide repeatedly to form the blastocyst.
In conclusion, the centromere is the site of chromosome attachment to the fibers of spindle. It is a region of the chromosome where the two sister chromatids are held together. The centromere is also the site of attachment of the chromosome to the spindle fibers during mitosis and meiosis.