Cell size is primarily limited by the cells' ability to get rid of wastes and the surface area-to-volume ratio. As a cell grows, its volume increases faster than its surface area. This affects the cell's ability to efficiently exchange materials (nutrients and waste) with its environment.
While the other factors mentioned, such as the amount of cytoplasm, the size of the nucleus, and the size of the plasma membrane, may also play a role, they are not the primary limiting factors in cell size. The efficiency of nutrient uptake and waste elimination is critical in maintaining cellular function, hence why the ability to get rid of wastes is a key limiting factor.