Latitude is not a factor in marine life divisions.
Answer:
How many cells are in the organism will help the scientist decide if the organism is unicellular or multicellular.
Explanation:
How many cells are in the organism will help the scientist decide if the organism is unicellular or multicellular because A unicellular organism is an organism that have one cell or it is single celled organism while a multicellular organism have many cells present or it is comprises of many cells.
The number of cells will determine if the organism is single cell or multicellular.
Natural selection is the correct answer