Final answer:
Multicellular organisms are characterized by having specialized cells that form tissues, organs, and organ systems that work together to carry out various functions.
Step-by-step explanation:
The correct characteristic of multicellular organisms is that 'They can possess tissues and organs,' and 'Their cells perform varied functions.' Multicellular organisms are composed of numerous cells which are specialized to carry out different functions, such as forming tissues, organs, and organ systems. The development and organization of these cells into structures are coordinated, where similar cells combine to create tissues, and these tissues collaborate to form organs with distinct functions. In turn, these organs work together within organ systems. The complexity of multicellular organisms allows for division of labor, with specific cells handling particular life processes.
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