The brain is covered by

The correct answer is D. All the above.

The brain is covered by three layers of membranes called meninges. The outermost layer is called the dura mater, the middle layer is called the arachnoid mater, and the innermost layer is called the pia mater. The meninges protect the brain and spinal cord from injury.

The brain is also surrounded by a fluid called cerebrospinal fluid (CSF). CSF helps to cushion the brain and spinal cord and to remove waste products.

The brain is encased in the skull, which is made of bone. The skull protects the brain from injury.

The meninges, CSF, and skull work together to protect the brain from injury.