What fluid is produced in the brain's ventricles and bathes the meninges?

Cerebrospinal fluid (CSF) is a clear, colorless fluid that is produced in the brain's ventricles, specifically by the choroid plexus within these cavities. This fluid plays critical roles in the central nervous system, including cushioning the brain and spinal cord, providing buoyancy, and serving as a medium for the exchange of nutrients and waste products between the blood and the central nervous system.

CSF bathes the meninges, which are the protective membranes surrounding the brain and spinal cord. By doing so, it helps to protect the brain from injury and serves as a barrier to pathogens. The production and circulation of cerebrospinal fluid are essential for maintaining the homeostasis of the brain's environment.

In contrast, synovial fluid primarily lubricates and nourishes joints, interstitial fluid refers to the fluid that exists in the spaces between cells, and plasma is the liquid component of blood. Each of these fluids has distinct functions and locations in the body, making cerebrospinal fluid the only appropriate answer in the context of this question.