**Core Concept**
The volume of cerebrospinal fluid (CSF) in adults is a critical aspect of neurology and neurosurgery, playing a key role in maintaining intracranial pressure and cushioning the brain. The volume of CSF is influenced by factors such as age, body size, and hydrocephalus.

**Why the Correct Answer is Right**
The correct answer is approximately 125-150 mL. This volume is produced at a rate of 0.3-0.4 mL/min by the choroid plexus in the ventricles of the brain. The CSF is then circulated through the ventricular system and the subarachnoid space, eventually being reabsorbed into the bloodstream at a rate of 0.5-1 mL/min. The balance between CSF production and reabsorption is crucial to maintaining normal intracranial pressure.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a plausible volume for the total CSF in an adult, as it would be significantly below the normal range.
**Option B:** This option is also too low, and the actual volume of CSF in an adult is higher than this.
**Option C:** This option is the correct answer, indicating that the total volume of CSF in an adult is approximately 125-150 mL.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the volume of CSF can vary depending on the age and size of the individual. In cases of hydrocephalus, the volume of CSF can be significantly increased, leading to increased intracranial pressure.

**Correct Answer: C. 125-150 mL**