Which of the following value represent the normal CSF glucose level in the normoglycemic adult?

CSF is produced in the choroid plexus of each lateral ventricle, exits the brain the foramen of Luschka and Magendi, and flows over the cerebral coex. From there it is absorbed into the venous system along the superior sagittal sinus. Approximately 150 mL of CSF is contained within the ventricles and surrounding the brain and spinal cord. Normal CSF is colourless, opening pressure is 70 -200mm water, has <5 neutrophils/mcL, glucose is 40-70mg/dl and protein is 15 - 45mg/dl. Ref: Pocket Guide to Diagnostic Tests, 5th Edition; Harrison's Internal Medicine, 18th Edition, Chapter 275