Which of the following is the innermost layer of the meninges?

The pia mater is the correct answer because it is the innermost layer of the meninges, which are the protective membranes covering the brain and spinal cord. It is a delicate layer that closely adheres to the surface of the brain and spinal cord, providing essential support and nourishment as it contains blood vessels that supply these structures. The pia mater is instrumental in maintaining the health of the central nervous system.

In contrast, the arachnoid mater is the middle layer of the meninges, positioned between the pia mater and the dura mater, while the dura mater is the outermost and toughest layer that provides the first line of defense against injury. Connective tissue, although present in the meninges, is a more general term and does not specifically refer to any of the meningeal layers. Understanding the layers of the meninges and their functions is crucial in the context of neuroanatomy and clinical situations involving the central nervous system.