The organelle responsible for moving fluid and distributing materials within a cell is the cytoplasm.

Here's why:

* Cytoplasm: This is the gel-like substance that fills the cell and surrounds the organelles. It's not a single organelle itself, but rather the medium through which materials move.

* Cytoplasmic Streaming: This is the movement of the cytoplasm, which helps distribute nutrients, waste products, and other materials throughout the cell.

While other organelles play a role in specific transport functions (like the Golgi apparatus for packaging and the endoplasmic reticulum for protein synthesis), the cytoplasm itself is the primary medium for overall fluid movement and material distribution.