What does the term "division of labour" refer to in multicellular organisms?

The term "division of labour" in multicellular organisms specifically refers to the concept of different cell types performing specialized functions. In multicellular organisms, cells differentiate and specialize to carry out distinct roles that contribute to the organism's overall function and survival. For instance, muscle cells are specialized for contraction, while nerve cells are adapted for transmitting signals. This specialization allows organisms to become more efficient and complex, as various tasks, such as metabolism, movement, and communication, can be performed simultaneously by different types of cells.

In this context, cellular differentiation is a process that leads to the division of labour by creating specialized cell types, but the term itself more directly points to the active roles these cells play. Gene expression relates to how specific genes are activated in different cells, leading to differentiation, but it does not capture the essence of the term "division of labour." Cellular reproduction refers to the process by which cells divide and replicate, which is separate from the functional specialization of cells within a multicellular organism. Thus, C is the most appropriate choice as it encapsulates the concept of different cell types undertaking specific roles in a coordinated manner to maintain the organism's homeostasis and health.