The correct answer is: C. Centrosomes
A centrosome is a small organelle found in animal cells that serves as a microtubule organizing center (MTOC). It is composed of two centrioles, which are short, cylindrical structures that are perpendicular to each other. The centrioles are surrounded by a cloud of pericentriolar material (PCM), which contains proteins that are involved in microtubule nucleation and organization.
During cell division, the centrosomes duplicate and move to opposite poles of the cell. The microtubules that are nucleated by the centrosomes form the mitotic spindle, which is responsible for separating the chromosomes during mitosis.
Blastomeres are the cells that are produced by the cleavage of an embryo. They are small, undifferentiated cells that are all identical to each other. The number of blastomeres increases as the embryo develops, and eventually they form the blastocyst.
Chromosomes are thread-like structures that contain the genetic material of a cell. They are made up of DNA and proteins, and they are found in the nucleus of the cell. Chromosomes are duplicated during cell division, and they are passed on to daughter cells.
Ribosomes are small organelles that are found in the cytoplasm of cells. They are responsible for protein synthesis. Ribosomes are made up of proteins and RNA, and they are the site of protein synthesis.
In conclusion, the correct answer is: C. Centrosomes.