Question

what is the fundamental difference between a unicellular and a multicellular organism? one lives in water, while the other lives on land. one has a nucleus, while the other does not. one is made of a single cell, while the other is made of many cells. one can move, while the other cannot.

Explanation:

Unicellular organisms consist of a single cell, while multicellular organisms are composed of many cells. This is the fundamental difference. The first option about living in water or on land is not a fundamental difference as both can be found in various habitats. The second option about having a nucleus is incorrect as both can be prokaryotic (no nucleus) or eukaryotic (with nucleus). The fourth option about movement is also not a fundamental difference as both can have the ability to move or not.

Answer:

One is made of a single cell, while the other is made of many cells.