Which type of organism is the most complex?

Answer: Eukaryotic, multicellular

Explanation:

There organism are known to be most complex group of organism as they have a variety of cells employed for performing different functions.

They have gone through the process of cell differentiation and have different cell organelles inside a cell performing different tasks.

Example: The cell organelles such as Nucleus, Golgi apparatus, vacuoles perform different functions.

Vertebrates is the organism that is most complex