The spindle apparatus of animal cells centers on a cell structure called the chromatid centromere centriole mitochondria

Correct D) Centrioles

A centriole is a cylindrical shaped organelle , which is made up of composed  of tubulin protein. They are found in the eukaryotic cells.

It is found as a paired structure in the centrosome. The centrioles are made of bundles of microtubules.

The position of centriole determine position of nucleus. It play an important role in the cell division. The main function of centrioles is to help in cell division in animal cell. They help in formation of spindle fibers that are used to separate the chromosome during the cell division.

prophase: we can observe the chromosomes to coil up and condense. they become visible. nuclear membrane and envelope disintigrate.s

metaphase: chromosomes align at the center, the metaphase plate. spindle fibers attach to centromeres of the sister chromatids. they meet at kinetochores.

anaphase: sister chromatids are pulled towards each opposing centromere, set on different poles.

telophase: chromosomes are now clustered up only on either sides of the cell. nuclear membranes reform, and a new cell wall forms along the cell plate. this will lead to cytokinesis, the process that divides the cell membrane and forms the cell wall.