__________ serve as the cytoskeleton of the brain. They support the function of neurons by insulating, repairing, and nourishing them.

A. Glial cells
B. Dendrites
C. Axons
D. Cell bodies

The correct answer is A. Glial cells. Glial cells, also known as neuroglia or simply glia, are non-neuronal cells in the brain that are essential for the functioning of neurons. They play a crucial role in supporting the neurons by providing structural support and insulation, repairing damage, and nourishing them.

To arrive at this answer, you can use your knowledge of the different cell types in the brain and their functions. Understanding the roles of different brain cells helps you determine which one serves as the cytoskeleton of the brain.

To further confirm this answer, you can also rely on reliable sources such as neuroscience textbooks or reputable scientific websites that describe the functions and roles of glial cells in supporting neuronal function.