Question

how is the relationship between cells, tissues, organs, and systems defined in a multicellular organism?
organs combine to form cells, which combine to form tissues, and tissues work together in systems.
systems combine to form organs, which combine to form tissues, and tissues work together in systems.
cells combine to form tissues, which combine to form organs, and organs work together in systems.
tissues combine to form cells, which combine to form organs, and organs work together in systems.

Explanation:

In a multicellular organism, cells are the basic unit. A group of similar cells forms a tissue. Different tissues combine to make an organ. And multiple organs work together to form an organ - system.

Answer:

Cells combine to form tissues, which combine to form organs, and organs work together in systems.