If A shows the formation of a contractile ring just prior to cytoplasmic division, the cell being observed is most likely an animal cell undergoing cytokinesis.

Here's why:

* Contractile Ring: The contractile ring is a structure made of actin filaments and myosin that forms beneath the plasma membrane during cytokinesis in animal cells. It constricts, pulling the plasma membrane inward and dividing the cytoplasm into two daughter cells.

* Cytokinesis: This is the process of dividing the cytoplasm of a cell after mitosis or meiosis.

* Animal Cells: Plant cells use a different mechanism for cytokinesis involving the formation of a cell plate.

Therefore, the presence of a contractile ring strongly suggests an animal cell undergoing cytokinesis.