Final answer:
The false statement on Jemin's poster is that unicellular organisms live longer, which is not necessarily true as lifespan depends on various biological factors.
Step-by-step explanation:
The statement on Jemin's poster that is NOT true is option A) Unicellular organisms live longer.
Unicellular organisms are indeed made up of just a single cell, making statement C) true. Additionally, multicellular organisms have cells that work together in a specialized manner to form tissues, organs, and organ systems, verifying that statement D) is true. When it comes to the comparison of size, multicellular organisms are indeed generally larger than unicellular organisms because multicellular entities are comprised of many cells, confirming that statement B) is true. However, the lifespan of an organism is not determined by whether it is unicellular or multicellular, but by a variety of biological factors. Therefore, the generalization that unicellular organisms live longer is not accurate, making statement A) the incorrect one.