Final answer:
The cell cortex of eukaryotic cells is made of a network of actin filaments, which are essential for maintaining cell shape and providing structural support just beneath the cell membrane.
Step-by-step explanation:
In eukaryotic cells, the cell cortex is primarily made up of a network of actin filaments, also known as microfilaments. These actin filaments are key to maintaining the cell's shape and are often found just beneath the cell membrane, supporting the cell and aiding in its movement.
While the eukaryotic cytoskeleton as a whole includes intermediate filaments and microtubules as well, the cell cortex specifically refers to the layer that is rich in actin filaments. Therefore, the correct answer to the question about what the cell cortex is made of is C. A network of actin filaments.