Answer:
Option). Centriole.
Step-by-step explanation:
Centrioles are small, cylindrical cell organelles, present near the nuclei of animal cells. They are involved in formation of spindle fibers at the time of cell division that help in proper separation of chromosomes during cell division. Plant cells do not have centrioles.
Nucleus and ribosomes are present in both animal and plant cells, while cell wall is found only in plant cell. Thus, the organelle in diagram that should be listed under 'animal only' will be 'centriole.'